Hepatitis A virus (HAV) is a food and water-borne agent primarily transmitted by fecal-oral route and has worldwide distribution. An inverse relationship has been observed between prevalence of HAV infection and standards of hygiene and sanitation in a community [Arankalle,2004].In countries where hygienic and environmental conditions have improved in recent decades, new infections are uncommon because general exposure to the HAV is low [Feinstone and Gust, 2000]. Most of the developing countries are in different phases of transition as far as hepatitis A is concerned [Arankalle, 2004].The present study included 182 volunteered medical students, of the middle socio-economic status, Kasr el Aini, Medical School, Cairo University. The included group of students was from the pre-clinical, clinical and house officers with negative history of jaundice, elevated liver enzymes and hepatitis A vaccination. The age of the studied subjects ranged between 17-30 years old. The age is further subdivided into two age groups : 17-20: Pre-clinical students.>20-30: Clinical students and House officers.The included subjects were further subdivided according to the results of the serosurvey into the seropositive and the seronegative groups.The studied group was subjected to:1- Full history taking:a- Personal history (age, sex, education status, schools of graduation).b- Socio-economic status (occupation of the father, residence).c- Sources of drinking water (piped water supplied as tap water & tank's water; bottled water). d- Sources of food intake (indoor and outdoor), level, frequency, longevity of outdoor food intake. History suggestive of food borne diseases (diarrhea, dysentery, food poisoning, enteric fever).f- History of the risk of exposure to hepatitis A infection (jaundiced patients, hospital admission, travel and camping). 2- Thorough clinical examination.3- Laboratory investigation included ELISA test for the detection of total antibodies to HAV in human serum.The laboratory serosurvey revealed 19.2% of the studied subjects were seronegative (non-immune) and 80.8% were seropositive (immune).With respect to the age, 55.6% of the 17-20 years old group were seronegative, while 17.3% of the >20-30 years old group were seronegative for HAV IgG with a statistically significant difference (P=0.01), signifying that students younger than 20 years old were more prone to hepatitis A infection than those at >20-30 years old.As regards the education status, the preclinical, clinical and the house officer groups showed that 55.6%, 23.8% and 8.3% were seronegative, respectively, with a significant statistical difference (P=0.01) signifying that the pre-clinical group was the most prone to hepatitis A infection.Non-significant statistical difference was detected as regards the sex distribution and the schools of graduation.As regards the socio-economic status, including the occupation of the fathers and the residence, no significant statistical difference was detected comparing the seronegative and the seropositive groups (P>0.05). Concerning the water supply, no significant difference was detected between both groups.Comparing both groups, concerning the outdoor food intake:There was no statistical significant difference as regards the source and the longevity of exposure to the outdoor food intake (P>0.05); while there was a highly significant statistical difference (P<0.05) as regards the level of place and the frequency of outdoor food intake signifying that the low level of outdoor food intake and the increase in the frequency of outdoor food intake are associated, respectively, with higher risk of HAV infection The multivariate regression analysis of education grading, level of outdoor food intake and the food borne diseases on comparing both groups, revealed significant statistical difference concerning the low level of outdoor food intake at different grading of education in the presence and absence of food borne diseases concluding that the low level of outdoor food intake increase the risk of HAV infection at the different education grading in the absence and presence of food borne diseases. Similarly the stepwise logistic regression analysis revealed significant difference as regards the age grouping as well as the low level of outdoor food intake confirming the age younger than 20 years old and the low level of outdoor food intake are associated, respectively, with higher risk of HAV infection.Taking into consideration the existence of multiple risk factors of food borne diseases and their abscence, on comparing both groups, there was a highly significant statistical difference (P= 0.01) with significant OR and CI stating that the seropositive group were the most prone to the risk of HAV infection. On the other hand, non-significant statistical difference (P>0.05) was detected as regards the other risk factors including exposure to jaundiced patients, hospital admission, traveling and camping.From the present study it was concluded that :The seroprevalence of hepatitis A of the middle socio-economic level, medical students is 80.8% in the age ranging between 17-30 years old. Approximately 20 percent of the studied group were non-immune with the age group between 17-20 years old was the most prone to the risk of HAV infection. The preclinical medical students occupied the majority of the non-immune group. The seroprevalence of hepatitis A is increasing parallel to the age. There was significant statistical difference as regards the level of place and the frequency of outdoor food intake and the history of food borne diseases signifying that the low level of place and the increase of frequency of outdoor food intake and the history of food borne diseases are associated with increase in the risk of HAV infection.There was no significant difference detected as regards the sex, SES, sources of drinking water, sources and longevity of outdoor food intake, exposure to jaundiced patients, hospital admission, traveling and camping.