Dissolution of three component tablets containing paracetamol (APAP), propyphenazone (PP), and caffeine (CAF) was carried out by USP paddle method. Three chemometric methods; inverse least square (ILS), principal component regression (PCR) and partial least squares (PLS) were applied to simultaneous assay of APAP, PP and CAF in tablets. The PCR, PLS and ILS methods were applied to simultaneous dissolution APAP, PP and CAF in tablets using a double beam UV-Vis spectrophotometer without any chemical separation and any graphical treatment of the overlapping spectra of three drugs. Twenty-two mixture solutions in different concentrations were prepared in simulated gastric juice (SGJ, USP) for the chemometric calibrations as training set. The absorbance data matrix was obtained :by measuring the absorbance at 14 wavelength points (from 222.5 to 292.5 nm) with the intervals of 5 nm (Deltalambda = 5 nm) in the spectral region between 200 and 310 nm. Training set and absorbance data were used for the calibrations of chemometric methods. The developed calibrations were tested for the previously prepared solutions of mixture of three drugs for the validation of the assay method. The chemometric calculations were performed by using the 'MAPLE V' software. The results of three chemometric methods were statistically compared with each other. These chemometric calibrations were successfully applied to the content uniformity and dissolution of the multicomponent tablets without any separation procedure. The synthetic mixtures of three drugs were used for the validity of the calibrations. Means recoveries (percent) and relative standard deviation of PLS, PCR and ILS methods were found to be 100.1 +/- 0.6, 101.4 +/- 1.6 and 100.1 +/- 0.6 for APAP; 100.9 +/- 3.2, 102.0 +/- 3.3 and 100.9 +/- 3.2 for PP; 99.9 +/- 3.5, 101.6 +/- 3.3 and 99.9 +/- 3.2 for CAF, respectively. Dissolution profiles of three component tablets were performed. More than 95% of drugs were dissolved within 15 min. All of the three-chemometric methods in this study can be satisfactorily used for the quantitative analysis and for dissolutions test of multicomponent dosage form. (C) 2002 Elsevier Science B.V. All rights reserved.