Six patients infected with Cydospora cayetanensis who soughtmedical care at three different hospitals in Turkey are hereinpresented.Four patients were male and the others werefemale and their ages ranged from 7 to 62 years.The firstpatient was HIV-positive and presented with watery diarrheawith a frequency of up to 18 times a day for more than tenmonths and diagnosed as cyclosporiosis in Kayseri,1996.The second patient was also HIV positive and diagnosed ascyclosporiosis in Kayseri,2000.The third patient was anacute myeloblastic leukemia(AML)patient and diagnosedin Istanbul,2000.The fourth patient was idiopathic hepaticcirrhosis complaining of diarrhea and weakness anddiagnosed in Kayseri,2001.The fifth and sixth patients wereimmunocompetent patients complaining of diarrhea anddiagnosed in Izmir and Kayseri,2002.Diarrhea occurringfrom one to ten times a day conlJnued for 7 to 70 d in the last5 patients.Treatment with a trimethoprim/sulfamethoxazolecompound was done for all patients.Both symptomatic andparasitologic improvements were quickly observed.Insummary,C.cayetanensis infection is rare in Turkey andmost patients infected with this pathogen tend to beimmunosuppressive individuals at present. Six patients infected with Cydospora cayetanensis who soughtmedical care at three different hospitals in Turkey arepresented. Flow of patients were male and the others werefemale and their ages ranged from 7 to 62 years.The firstpatient was HIV-positive and presented with watery diarrheawith a frequency of up to 18 times a day for more than ten months and diagnosed as cyclosporosis in Kayseri, 1996. The second patient was also HIV positive and diagnosed as cyclosciosis in Kayseri, 2000. third-patient was anacute myeloblastic leukemia (AML) patient and diagnosed in Istanbul, 2000 . The fourth patient was idiopathic hepaticcirrhosis complaining of diarrhea and weakness and diagosis in Kayseri, 2001. Fifth and sixth patients were immunocompetent patients complaining of diarrhea and diagosis in Izmir and Kayseri, 2002. Diarrhea occurring from one to ten times a day conlJnued for 7 to 70 days in the last 5 patients. Treatment with a trimethoprim / sulfamethoxazolecompound was done for all patients. Bot h symptomatic and parasitologic improvements were rapidly observed. Insummary, C. cayetanensis infection is rare in Turkey and most patients infected with this pathogen tend to be immunosuppressive individuals at present.