Sustained release phenylpropanolamine HCl tablets were prepared with compritol as a retardant material. The effects of varying wax levels and methods of matrix formation on drug release were investigated. Also the compaction profiles were recorded for all formulations. The amount of drug in the formula was held constant (10% w/w), while the wax level was varied from 10% to 50% w/w. Two methods were used for the preparation of drug: wax systems; physical mixture and solid dispersion. The drug release from tablets containing 10% Compritol and prepared by solid dispersion was 97% after six hours of testing dissolution. Tablets prepared with 30% wax released 72% of the drug, while tablets containing 50% wax released only 30% of the drug after six hours. Tablets prepared by physical mixture gave higher drug release than tablets prepared by solid dispersion method. The incorporation of Compritol decreased the ejection forces of tablets during compaction. The drug release from tablets prepared by solid dispersion followed the diffusion controlled model described by Higuchi for inert porous matrix.