Kinetic and clinical evaluation of cefotiam, a new cephalosporin, is reported. It was found that the drug is rapidly distributed to the tissues. Equilibrium between tissues and plasma is reached in about an hour. Some 90-91% of the dose administered is excreted in the urine, and accumulation does not occur. A clinical cure was obtained in 27 of a series of 35 patients (77.1%). Improvement was observed in 7 cases (20%). The antibiotic proved ineffective in the remaining cases (2.8%). Tolerance was excellent and there were no side-effects worthy of note.