12 patients with urinary tract infection (UTI) were treated with cephalexin, 750 mg 6-hourly for 14 days, resulting in a 75% cure rate as evidenced by a mere fortnight's follow-up. Side effects, including 2 alarming ones, were observed in 4 patients. The symptoms were severe gastrointestinal disturbances including enormous swelling of the tongue, central nervous system disturbances, slight thrombocytopenia, and eosinophilia. It is suggested that cephalexin should not be the first drug of choice in treatment of UTI. However, it may be useful in selected cases. The dosage schedule must be guided by renal function studies.