In a cross-sectional study conducted in children referred to Bandar Abbas Pediatric Hospital in southeastern Iran, the prevalence of Cryptosporidium infection was 7%. Diarrhea lasted significantly longer in children infected with Cryptosporidium. There were also a significant association between Cryptosporidium infection and underweight children and no association with parent's occupation, breast-feeding, source of drinking water, vicinity or presence of sewage or animal exposure.