Dengue is seldom recognized as an imported disease in Europe. A prospective clinical study was carried out in 37 travelers suspected to have dengue infection on their return from dengue-endemic areas. Anti-dengue antibodies were found in 24 of 37 patients (14 recent infections and 10 undetermined). The most common features among the recent infections were fever (100%), thrombocytopenia (61.5%), abnormal liver function tests (61.5%), and rash (53.8%). In one case, denguehemorrhagic fever grade III was confirmed and later followed by depression and suicide of the patient. The possibility of local transmission of dengue in Spain is discussed.