Hospital records of 130 patients with fever of unknown origin (FUO) from 1985 to 1989 were studied. Etiologic diagnoses were made in 117 (90%) patients, 60 (46.1%) patients had infections, 22 (16.9%) neoplasms, 19 (14.6%) connective tissue diseases, and 16(12.3%) various diseases grouped under "miscellaneous", 10% of the FUO cases remained undiagnosed and the death rate was 13.8%. This clinical analysis showed that infection was the most frequent cause of FUO in this series.