Thirty-one cases of human listeriosis seen from 1971-1999 were reviewed. cases were grouped as follows: Group I composed of 14 patients were studied in the period 1971-1984; and group II composed of 17 cases studied in the period 1985-1999. We tried to assess changes in the incidence, clinical findings and outcome in both periods. The incidence of listeriosis remained constant along the years, 1.2 cases/20,000 discharges. The mean age of the patients significantly increased along the years (55 11 years versus 68 12 years; p 0.002). 77% of cases had one or more underlying diseases predisposing to listeriosis. We observed an increasing number of listeriosis in patients without chronic diseases in recent years. Listeriosis presented as meningitis or primary sepsis. Mortality was 61% and was strictly associated with the severity of the underlying disease. Patients with meningoencephalitis and seizures had a worse prognosis. We did not observe differences in mortality of patients who were treated with beta-lactam monotherapy in comparison with those who were treated with beta-lactam/aminoglucoside combination. Cotrimoxazole was uniformly successful treatment of human listeriosis in this series.