OBJECTIVE: To determine the contents of chlorzoxazone and paracetamol in compound chlorzoxazone tablets by Kalman Filter spectrophotometry. METHODS: The absorbabilities of the two components were detected in an interval of 1mn over a wavelength range of 248～296 nm. The data obtained were computed by Kalman Filter program. RESULTS: Good linear relations were achieved when the concentration ranges of chlorzoxazone and paracetamol were 2～20 ?g?mL-1 (r=0.999 9) and 3～30 ?g?mL-1 (r=0.999 7) respectively; the recovery rates were 99.1%(RSD=1.01%) and 100.3% (RSD=0.92%), respectively. CONCLUSION: This method is simple, rapid and accurate, and it can be used for the simultaneonsly determination of 2 components in compound chlorzoxazone tablets without separation.