Relapsing peritonitis due to Mycobacterium xenopi developed in an 80-year-old man undergoing continuous peritoneal dialysis after appropriately treated concurrent bacterial peritonitis. The patient presented with a lymphocytic exudative peritoneal drainage fluid. The diagnosis of tuberculous peritonitis was made by identification of acid-fast bacilli in peritoneal effluent and culture of M. xenopi. Oral antituberculous drugs in combination with intraperitoneal streptomycin achieved suppression of the disease, permitting peritoneal dialysis to be continued with satisfactory clearance and ultrafiltration capacity during a follow-up period of up to 35 months. Streptomycin kinetics revealed that 75% of the intraperitoneally administered dose of streptomycin is absorbed from the dialysate.