Simple, fast and reliable derivative spectrophotometric methods were developed for determination of indapamide in bulk and pharmaceutical dosage forms. The solutions of standard and the sample were prepared in methanol. The quantitative determination of the drug was carried out using the first-derivative values measured at 252.8 nm (N = 6) and the second-derivative values measured at 260.4 nm (N = 9). Calibration graphs constructed at their wavelengths of determination were linear in the concentration range of indapamide using peak to zero 1.00-30.00 mug ml(-1) for first-derivative and 1.00-35.00 mug ml(-1) for second-derivative spectrophotometric method. The developed methods were successfully applied for the assay of pharmaceutical dosage forms which do not require any preliminary separation or treatment of the samples. The details of the statistical treatment of analytical data are also presented. The results obtained from two derivative spectrophotornetry were compared with a spectrophotometric method reported in literature and no significant difference was found statistically. (C) 2002 Elsevier Science B.V. All rights reserved.