Cryptosporidium spp. is one of the leading causes of parasitic diarrhea. It is the most common parasite in humans all over the world with Giardia. Cryptosporidium is an important cause of chronic diarrhea in Human Immunodeficiency Virus (HIV)/Acquired Immunodeficiency Syndrome (AIDS) patients. Patients with normal immune system may have an asymptomatic course or clinical presentation such as acute watery diarrhea without blood and persistent diarrhea. The severity and duration of the disease may be a reflection of the immune deficiency. Children under two years of age and children with malnutrition may have a risk of prolonged Cryptosporidium spp. infection, even if immunodeficiency work-up is normal, as they may have defects in the natural immune system and lymphocyte functions. Cryptosporidium spp. oocysts contaminate water sources, swimming pools, vegetables and fruits because oocysts are partially resistant to chlorination. So it may be problem for public health. Pets, livestock and humans can be carriers of Cryptosporidium spp. Factors such as developmental level of the countries, immune system, nutritional status, living in crowded environments, contact with contaminated water, close contact with animals, working at a hospital and hot and humid climate affect the incidence of Cryptosporidiosis. Cryptosporidium spp. may cause asymptomatic infection, mild diarrheal disease or severe diarrhea with high volume, which may be accompanied by nausea, vomiting, abdominal pain and fever, following a 1-7 day incubation period. Diarrhea may be acute or chronic, transient, intermittent, or continuous; loss of fluid can be up to 25 L/day in severe diarrhea. Cryptosporidium spp. are mainly located in intestines, but non-intestinal (bile ducts, pancreas, stomach, respiratory system, kidney) involvement may occur in immunocompromised patients. Hepatobiliary system involvement occurs in 10-30% of patients with AIDS; stone-free cholecystitis can lead to sclerosing cholangitis and pancreatitis. Hepatobiliary involvement is not expected in patients without immunodeficiency. In this article, we present a case of Cryptosporodiosis with hepatobiliary system involvement who were admitted to the pediatric emergency clinic with the complaints of severe diarrhea and Cryptosporidium spp. oocysts were detected in parasitological examination of the stool specimen. Immunodeficiency was not considered with her resume and laboratuary examinations. We would like to emphasize that Cryptosporodium spp. may be the cause of severe acute diarrhea in non-immunocompromised patients and may also involve hepatobiliary system involvement.