Background: The occurrence of Giardia duodenalis in cats is of potential significance from both clinical and public health perspectives. The object of this study was antigenic detection of G. duo­denalis in house­hold cats of Ahvaz district, South-West of Iran.Methods: The prevalence of G. duodenalis was determined in fecal samples by two techniques: centrifuga­tion-flotation and a commercial Giardia Antigen Test Kit (immunochromatography assay) in 150 household cats of different ages among referred cases to Veterinary Hospital of Ahvaz University from January 2008 to February 2010.Results: Five out of 150 fecal samples (3.33%) were positive for antigen of G. duodenalis by immunochromatography assay. The prevalence was significantly higher in young cats less than 6 months (15.79%) compared with adult cats 6 months - 3 years (1.37%) (P=0.027) and above 3 years (1.72%) (P=0.044). The infection had more prevalence in diarrheic cats (17.39%) com­pared with non-diarrheic cats (0.79%) and the difference was significant (P=0.02) as well. The prevalence was higher in male cats (3.41%) than females (3.23%) and in the season of autumn (6.06%), but the difference was not significant between the prevalence of infection relative to host gender and season (P>0.05). Microscopy examination on fecal samples showed that 2% of the studied cats were positive.Conclusion: The parasite antigen was present as a zoonotic infection in Ahvaz district, South-west of Iran. More sensitive techniques, such as immunochromatography assay, might yield more reli­able results, in the detection of low levels of Giardia in fecal samples of cats.