An accurate, simple, reproducible and sensitive method for the determination of acetylsalicylic acid, caffeine and codeine phosphate has been developed and validated. Acetylsalicylic acid, caffeine and codeine phosphate were separated using a microBondapack C(8) column by isocratic elution with flow rate 1.0 ml/min. The mobile phase composition was 125/125/250/0.5 (v/v) isopropyl alcohol, acetonitrile, water and o-phosphoric acid. The samples were detected at 215 nm using photo-diode array detector. The linear range of detection for acetylsalicylic acid, caffeine and codeine phosphate were between 0.40 and 1000, 0.25 and 250, and 0.48 and 96 microg/ml, respectively. The linearity, range, selectivity, system performance parameters, precision, accuracy, and ruggedness for acetylsalicylic acid, caffeine and codeine phosphate were also shown to have acceptable values.