We reviewed the notes of 30 patients treated between 1976 and 1991 for 31 episodes of penicillin-susceptible streptococcal endocarditis where the intention was to treat for 14 days. The mean age of the patients was 45 $pM 22 years; eight were women, and 23 were men. The mean duration of symptoms was 59 $pM 65 days. Treatments were between 12 x 106 and 20 x 106 U of intravenously administered benzylpenicillin per day, usually given 4 hourly, plus a mean 1.16 $pM 0.3 mg of intravenous gentamicin per kg per dose, usually given 8 hourly (or tobramycin in six episodes). The mean hospital stay was 19 $pM 3.8 days. With very strict criteria for failure, 29 episodes (94%) were cured and two were not. One of the treatment failures was among the five patients with histories longer than 3 months in duration. Two weeks' combination treatment with benzylpenicillin and gentamicin/tobramycin given intravenously is a cost-effective and safe therapy for penicillin-susceptible viridans streptococcal endocarditis.