Peanut production areas frequently suffer from drought, which can cause severe yield losses, increased aflatoxin, and compositional changes in seed. Midseason drought is generally the most detrimental to seed yields and in altering seed protein composition. The purpose of this study was to investigate the effect of midseason drought on arginine content in peanut genotypes with different levels of drought resistance. The experiment was conducted under field conditions for 2 years. Two water regimes (well-watered conditions and no irrigation during 30-60 days after planting) were assigned as main plots, and five peanut genotypes were arranged in subplots. Arginine content of mature peanut seed was analyzed at harvest. Midseason drought increased arginine content in all genotypes in both years. Variation in arginine content among peanut genotypes also indicated the possibility for breeding programs to improve arginine content in peanut.