This is the first case of human cyclosporiasis reported in Korea. We detected the oocyst of Cyclospora cayetanensis from a 14-yr old girl who complained of persistent diarrhea after traveling to Indonesia. Round oocysts sized about 8 to 9 µm with wrinkle on the wall were found in modified acid fast stained stool specimen. Stainability was variable from red to pale. Oocyst wall showed typical autofluorescence under ultraviolet illumination. The exact diagnosis for the cause of diarrhea and treatment for this patient were not provided at the right moment from the hospital since the diagnostic system for the Cyclospora infection was not ready in the clinical laboratory of the hospital. More attention should be paid on Cyclospora as a cause of diarrhea especially for those returning from a trip to the tropics and an adequate diagnostic system for the Cyclospora infection should be implemented in clinical laboratories as soon as possible.