The concentration of Latamoxef (LMOX) in the serum, prostatic tissue and bladder mucosal tissue of 20 patients with benign prostatic hypertrophy and bladder cancer was measured after intravenous infusion of 1 g or 2 g of LMOX. Serum, prostatic tissue and bladder mucosal tissue levels of LMOX responded satisfactorily to the dose of LMOX. The bladder mucosal tissue level was higher than the prostatic tissue levels. Judging from the inhibitory concentration of LMOX (MIC 80), the concentration was sufficiently effective against infections caused by gram-negative, gram-positive and anaerobic bacilli.