Sustained release theophylline tablets and capsules were prepared with dika fat, a solid vegetable oil extracted from the kernels of Irvingia gabonesis var gabonesis and var excelsia. Anhydrous theophylline was incorporated into dika fat by the fusion method. The in vitro release of the theophylline was monitored by the so-called half change dissolution method in stimulated gastric juice USP without pepsin and in stimulated intestinal juice without pancreatin, respectively. The USP XX paddle method was used. A level of sustained release was achieved over a 6-h period in both the tabletted and encapsulated dosage forms. The theophylline formulations containing dika fat, prepared in this study, exhibited dissolution profiles similar to those of Theo 24, Theodur and Respid, some commercial sustained release theophylline formulations.