This study served a twofold purpose in that it investigated the relationship of tannins to maturity of peanuts and provided some information on the possible importance of tannins in resistance of peanuts to invasion by various fungi. Peanut fruits were separated into selected physiological maturity stages and divided into hull, seed coat and seed. The fruit parts in each maturity stage were analyzed for tannin using Folin-Denis reagent. Examination of physical and chemical characteristics of hull and seed coat tannins confirmed they are both condensed tannins. Presented as mg tannin per fruit part, hull tannins increased significantly after stage 9, seed coat tannins increased significantly to stage 9 then decreased, and seed tannins did not change. Fruit parts of cured peanuts containing several maturity stages were similar in tannin content to the more mature uncured fruit parts. Calculated as % fresh weight, tannins in the hull and seed coat were significantly higher in the three most mature stages. The results show a close relationship of tannin and maturity and also indicate that tannin concentrations may be sufficient to provide some measure of resistance to microbial attack.