An HPLC procedure for the determination of theophyl lline in pharmaceutical preparations is described. A Spherisorb octadecyl-silane ODS-2 C18analytical column and spectrophotometric detection at 273 nm were used. Adequate retention was achieved with a mobile phase containing 0.05 M sodium dodecylsulphate (SDS) and 3% propanol at pH 7. The reproducibilities were 1.2 % and 1.7%for 3.8 and 7.6 μg/mL theophylline concentrations, respectively.