The stool samples of 75 patients with gastroenteritis and/or loose and watery faeces at three hospitals and one clinic in Zaria were examined for Cryptosporidium. The stool samples were concentrated by the formol–ether method and stained with safranin–methylene blue. Sixteen (21%) samples were positive. The rate of detection was higher among females (27%) than males (17%) and among adults (29%) than children (8%). The study confirmed the presence and possible significance of Cryptosporidium, which is a known zoonotic protozoan, in the aetiology of human gastroenteritis in Zaria, Nigeria.