The Italian multihospital study of bacteriuria in pregnancy randomized 153 pregnant bacteriuric patients to receive fosfomycin trometamol (FT) as a single dose of 3 g and 138 such patients to receive conventional therapy with pipemidic acid (PA), 400 mg b.i.d. for seven days. The two groups were well matched for age, parity, pregnancy course, symptoms and past history of cystitis. Infecting organisms were eradicated in 147 (96%) of FT and 129 (94%) of PA patients. Similar recurrence rates occurred. Minimal side effects (mostly nausea and dyspepsia) occurred (9%) FT; 15% PA). Single-dose FT appeared equivalent to conventional treatment with PA.