Abstract : The purpose of this study was to determine the dose uniformity among various brands of over-the-counter (OTC) melatonin tablets (or capsules). Melatonin is a substance that may be used by Army aviation personnel, so education in regards to the actual amounts of melatonin contained in each tablet will be beneficial. High-pressure liquid chromatography was used to analyze eight different brands of tablets. From each brand, two lots were selected and six tablets were taken from each lot for analysis. A liquid chromatograph equipped with a C-18 microbore column was used in conjunction with an autosampler to perform two runs per tablet, while also running intermittent standards on a regular basis. Of the brands tested, most were either consistently higher or lower than the amount stated on the label. Some brands showed significant variability. This variability is reason for concern for those users of OTC melatonin. Although such variability may not necessarily cause any side effects, it does indicate laxity in preparation techniques.