A rapid, accurate and precise PMR method is presented for the quantitative determination of codeine and codeine phosphate as bulk drugs and in tablet dosage form. The determination is based on the integration of the C-3 methylprotons or the two aromatic protons of codeine or its salt relative to that of the nine protons of t-butanol. Standard deviations of ± 1.39, 0.27 and 0.65% were obtained for codeine, codeine phosphate bulk drug and codeine phosphate tablets respectively. The method furnishes a specific means of identification of codeine as well as of the simultaneous detection and possible determination of morphine; thus fulfilling one of the most important pharmacopeial requirements for the purity of codeine.