Background and study aim: Hepatitis A is an acute, usually mild and self-limiting disease affecting the liver. We aim to assess the effect of oral N-acetyl cysteine compared with placebo on length of hospital stay in adult patients who were admitted to the hospital with acute hepatitis A which might cause earlier resolution of hepatitis. Subjects and Methods: 40 patients were diagnosed as acute hepatitis A and classified into two groups, the first one involved 20 patients who received oral N-acetyl cysteine and supportive treatment, and the second one involved also 20 patients but they received placebo and supportive treatment. We measured complete blood count (CBC), kidney profile (KP), liver function test (LFT),  blood glucose, C-reactive protein (CRP) and coagulation profiles  on the day of presentation, and every other day till the day of discharge from the hospital. Serological tests were done for HAV Immunoglobulin M (IgM), HEV IgM, HBsAg, HBcIgM, antibody to Hepatitis C virus. Results: The mean length of hospital stay in the NAC group was 13.2 days compared with 14.3 days in the placebo group. Length of hospital stay differed significantly between groups.  The mean time of reliving symptoms at presentation was 3.6 days in the NAC group and 4.4 days in the placebo group. The mean time of reliving symptoms at presentation was significantly lower in NAC group than in placebo group. Conclusion: use of oral NAC as adjunctive therapy for treatment of acute hepatitis A was safe in these patients and was associated with a shorter length of patient stay in the hospital.