The erythromycins are broadly reviewed from a clinical viewpoint. The antimicrobial spectrum, clinical indications, pharmacokinetics and toxicity are dealt with. The usefulness of erythromycin for respiratory tract infections is stressed. New evidence to support bactericidal activity of this antibiotic is noted. There seems little reason to use the potentially hepatotoxic estolate form of erythromycin. The safety of the other forms of this antibiotic available in this country is emphasized.