A new analytical procedure for fast and simultaneous determination of sulfamethoxazole (SMX), trimethoprim (TMP) and phenazopyridine (FZP) has been developed. The method is based on batch injection analysis with multiple pulse amperometric detection (BIA-MPA) which offers several desirable features, such as simplicity, reduced costs, robustness, good precision (RSD <3.5%, n = 15), high analytical frequency (up to 70 injections h(-1)) and generation of small volume of waste by analysis. The BIA-MPA procedure provides linear range from 4 to 320, from 2 to 40 and from 1 to 40 mg L-1 and limits of detection of 020, 0.15 and 0.05 mg L-1 for SMX, TMP and FZP, respectively. The results obtained with the proposed method were compared to those obtained by HPLC and similar results were obtained (95% confidence level). (C) 2016 Elsevier B.V. All rights reserved.