In this study, dietary intake of the amino acids lysine and arginine did not differ significantly between normal controls and patients with herpes virus. Both groups of subjects consumed significantly more lysine than arginine on a daily basis. Those results are not surprising given the American population's preference for high lysine foods, such as meat and dairy products, as opposed to foods high in arginine, such as legumes, whole grains, and nuts. The mean daily intakes of lysine and arginine for the 16 subjects studied were 8.11 gm +/- 2.28 and 6.32 gm +/- 1.74, respectively. The standard deviations of the mean intakes indicate that there is a large variability in the intake of both amino acids and the ratios of the two amino acids in individual diets. This information is important, considering the conflicting results obtained previously by researchers investigating the efficacy of lysine therapy for herpes infections. The extent of the variability in total amino acid intake or ratio of lysine to arginine in the diet cannot be determined from previous studies. More important, the possible effects of these ranges on the interpretation of study results remain unknown. In order for future studies to accurately determine the effects of supplemental lysine in the treatment of herpes infections, close monitoring of dietary intake is essential.