Giardiasis is the gastrointestinal illness caused by the flagellated protozoan Giardia intestinalis. Modified Wheatley's trichrome stain used as direct method in diagnosis of giardiasis and ELISA for detection of copro - antigen in stool of patients. ELISA was more sensitive in diagnosis , sensitivity ( 69.3%), specificity (80%), P.P.V (91.2%), N.P.V (46.5%). In control group (non diarrhoeic and asymptomatic apparently healthy subjects), (12%) were diagnosed positive for giardiasis by trichrome stain and (20%) were diagnosed by ELISA.