A spectrofluorometric method for the determination of the two antilipaemic drugs, lovastatin and semvastatin in plasma is described. The method was based on heating the drug with 0.1% orthophenelenediamine aqueous solution at 90°C(for 25 minutes for lovastatin and 15 minutes in case of semvastatin). The resulting reaction product, after dilution with methanol showed strong fluorogenic activity exhibiting wavelengths of maximum excitation and emission at 430 and 530 nm, respectively. The assay parameters were optimized to achieve maximum sensitivity and accuracy for the determination of the two drugs in spiked human plasma. The mean percentage recoveries of lovastatin and semvastatin from spiked human plasma samples in concentrations ranging from 0.3 to 0.9 µg ml^-1 were 99.76 ± SD 0.958 and 99. 903 % + SD 2. 45, respectively.