A total of 14,915 shigella isolates obtained in 1991-1996 from patients attending the Dhaka (urban) and Matlab (rural) treatment centres of the International Centre for Diarrhoeal Disease Research, Bangladesh were examined for susceptibility to ampicillin, co-trimoxazole, nalidixic acid, mecillinam and ciprofloxacin by a disc diffusion method. There were no ciprofloxacin-resistant shigella isolates. The prevalence of resistance to ampicillin, co-trimoxazole and nalldixic acid varied between isolates. It increased to similar degrees in isolates from both Matlab and Dhaka. However, resistance to mecillinam was more prevalent among isolates from Matlab than from Dhaka. The increase in mecillinam-resistant shigellae in the community may have grave implications for the empirical treatment of shigellosis in Bangladesh and other developing countries.