The theophylline and phenobarbital contents in long-acting aminophylline tablets was determined by HPLC on a μBondpack C18 column (10 mM, 3.9 mm x 300 mm) with MeOH-H2O (25:75) as mobile phase and detection at 220 nm.The linearity was in the range 11-26 μg and 0.6-1.5 μg for theophylline and phenobarbital, resp.The mean recovery was 101.2 and 100.8% with RSD 0.60 and 0.70% for theophylline and phenobarbital, resp.The method was simple and accurate.