Three assay procedures based on potentiometry, spectrophotometry and high performance liquid chromatography (HPLC) have been developed for the determination of tinidazole in tablets and injections. In the potentiometric titration method, the drug in glacial acetic acid is titrated with acetous perchloric acid with potentiometric end point detection. Spectrophotometry involves the addition of different amounts of tinidazole to a fixed amount of perchloric acid-malachite green mixture followed by measurement of absorbance at 615 nm. The HPLC determination was carried out on a reversed phase C-18 column using a mobile phase consisting of acetonitrile-0.1 % phosphoric acid (70:30) at a flow rate of 1.0 mL min(-1) with UV-detection at 316 nm. Potentiometric tiration is applicable over 1-10 mg range of tinidazole and in spectrophotometry, the calibration graph is linear from 15-180 mu g mL(-1) with a molar absorptivity of 9.02 x 10(2) L moL(-1) cm(-1) and a Sandell sensitivity of 385.2 ng cm(-2). The limits of detection and quantification are calculated to be 3.05 and 10.15 mu g mL(-1), respectively. In HPLC method, a rectilinear relationship was observed between 6.25 and 250 mu g mL(-1) tinidazole with a detection limit of 0.625 mu g mL(-1) and a quantification limit of 1.875 mu g mL(-1). The analysis time was less than 5 min. The statistical evaluation of the methods was examined by determining intra-day and inter-day precision. The methods when applied to the determination of tinidazole in tablets and injections gave satisfactory results. The accuracy and reliability of the proposed methods were further ascertained by parallel determination by the reference methods and by recovery studies using standard-addition technique.