During a 3-month pilot study, we identified ten children with cryptosporidiosis; they all presented with diarrhoea, most also with fever, vomiting and dehydration. For diagnosis, the formalin-acetate concentrate of the stool, and direct smears were stained for oocysts in safranin-methylene blue (S-MB). The negative staining of oocysts in trichrome-stained specimens was indicative and was confirmed by destaining and restaining in S-MB. Constraints contributing to the absence of reports from the Arabian Gulf were the lack of awareness of Cryptosporidium sp. as a cause of diarrhoea in children, inappropriate laboratory diagnostic techniques and, possibly, the initial referral of patients to polyclinics where mild cases may go undetected. Contaminated drinking water and close contact with domestic animals are possible modes of transmission of Cryptosporidium sp. but further studies are recommended to confirm this.