We tested the efficacy of a single daily dose of ceftriaxone (active ingredient of Rocephin^TM) for the treatment of severe bacteremic infections in 125 non-neutro-penic adult patients. A single daily dose of ceftriaxone ranging from 1 to 4 g was given. Surgical procedures were performed if needed. Seventy-six (60.8%) were males and bacteremia was nosocomially acquired in 45 (36%). Microbiologically proven bacteremia was demonstrated in all patients. The most common microorganisms isolated were Escherichia coli (46 episodes), Streptococcus pneumoniae (17 episodes), Klebsiella pneumoniae, and Haemophilus influenzae, Serratia marcescens, Salmonella sp., and Staphylococcus aureus (9, 7, 6, 6, respectively). The urinary tract was the source of the bacteremia in 45 cases (36%), and the lower respiratory tract in 33 (26.4%). Mean duration of treatment was 10.8 days (range 3–21 days). One hundred and six patients (84.8%) recovered completely, 11 (8.8%) improved, but needed an alternative antibiotic treatment. An alternative treatment was also given to a patient whose condition had initially deteriorated. Seven patients (5.6%) died. Death was directly related to the infection in 2 cases. Three patients (2.4%) developed a superinfection, and 5 (4%) a severe (1 case) or mild (4 cases) adverse effect. In summary, a single daily dose of ceftriaxone proved to be useful for the treatment of selected severe bacteremic infections.