Background & objectives: Parasitic infections are among important health problems all over the world especially in developing countries. Considering the epidemiological importance of parasitological diseases and necessity to evaluation the parasites prevalence in different areas and populations, current study aimed to determine the prevalence of intestinal parasites in patients admitted to the laboratories of Baqiyatallah Hospital in Tehran.

Methods: This is a retrospective cross sectional study in which stool examination reports of all referred patients (70978) to central and emergency laboratories of Baqiyatallah hospital were evaluated during 2010-2014. In this course, at least one stool sample of patients was assessed by direct smear and formalin-ethyl acetate methods. The data were analyzed using descriptive statistics in SPSS 16. Chi-square test was used for comparison of the prevalence.

Results: From 70978 patients, 42421(59.77%) and 28557(40.23%) were male and female, respectively. From 2617 infected individuals, 1841(70.3%) and 776 (29.7%) were males and females, respectively. The prevalence of pathogen and non-pathogen intestinal parasites was 2283(87.23%) and 334(12.76%) respectively. Also the prevalence of intestinal helminthes and protozoa in infected population was 0.42% and 99.57%, respectively. Blastocystis hominis and then Giardia lamblia were the prevalent parasites.

Conclusion: In current study the prevalence of parasites is lower than those reported in other investigations. Differences in geographical location, sample size, duration and type of study (prospective or retrospective) and study population may be effective agents. The higher prevalence of "Blastocystis hominis" in comparison with other parasites can attract more attention to improve the quality of laboratory and clinical diagnosis of this protozoa