1. Two cases of costal chondritis are presented. The special features and treatment of this condition are described and the literature is reviewed. 2. Early diagnosis and energetic treatment of costal chondritis obviates serious morbidity. 3. Treatment with antibiotics is of value in curing the condition before cartilage necrosis has occurred and in controlling the spread of infection to neighbouring tissues. 4. Excision of all necrotic cartilage is essential for cure, if cartilage necrosis has occurred. 5. Secondary infection with organisms of low virulence, notably pseudomonas pyocyanea, is nowadays the commonest cause of chronicity.