Technical Abstract: High performance liquid chromatography of dabsyl derivatives of amino acids was employed for quantification of physiologic amino acids in cucurbits. This method is particularly useful because the dabsyl derivatives of glutamine and citrulline are sufficiently separated to allow quantification of each. Water extraction of ground frozen-thawed tissues effected complete recovery of the physiologic amino acids as demonstrated by spiking experiments and tissue combination experiments. Physiologic amino levels were determined for cantaloupe, cucumber, straight-necked yellow squash, Botswana wild watermelon, and domestic watermelon. Comparison of L-citrulline levels in watermelon from different years, different cropping regions, or different stages of fruit maturity demonstrated that each of these parameters exert a marked influence on the citrulline content in a watermelon.