A 58-year-old man and his 60-year-old wife returned from a journey through Indonesia with complaints of persisting diarrhoea. In the stools of both patients we found oocysts of the parasite Cyclospora cayetanensis. We treated them with co-trimoxazole which resulted in fast clinical improvement. An infection with the parasite C. cayetanensis should be considered in travellers returning from tropical countries with persisting diarrhoea. Despite the self-limiting nature of the infection treatment with co-trimoxazole 960 mg 2 dd for 7 days may be considered in cases with a protracted course.