A rapid quantitative gas-liquid chromatographic procedure for the determination of 2-diphenylmethoxy-N, N-dimethylethanamine (diphenhydramine, dimedrol) hydrochloride, in pure form and when it is dispensed in eye drops and lotion, is described. The antihistaminic drug requires no conversion to the free base, and the assayed pharmaceutical formulations need no sample cleanup, preliminary drug separation or derivatization. The method is adopted for a concentration range varied between1.0 - 10 mg.ml−1of the drug in ethanolic solutions. The accuracy obtained was 98.6 ± 0.31%, 93.3 ± 0.82%, and 87.9 ± 1.1% for the authentic diphenhydramine hydrochloride, its eye drops and its lotion. The 50% - addition of the drug to the labelled claim in the galenical forms, eye drops and lotion, gives average mean recoveries of 100.8 ± 0.74% and 97.9 ± 0.45% respectively.