Since composition of the seed of peanut (Arachis hypogaea L.) is an important quality factor, the effect of the plant growth regulator, succinic acid 2,2 dimethylhydrazide (SADH, sold under the trade name Kylar), on seed composition needed investigation. Field tests were grown in Martin County, NC, on a Norfolk loamy fine sand (fine-loamy, siliceous, thermic Typic Paleudult) and in Suffolk, VA, on an Eunola loamy fine sand (fine-loamy, siliceous, thermic Aquic Hapludult) in 1981 and 1982. Peanut seed from treated and untreated plots of the cultivars ‘Florigiant’, ‘NC 6’, ‘NC 7’, ‘VA 81B’, and ‘NC 8C’ at each location were evaluated for fatty acid distribution, iodine value (IV), oleic/linoleic (O/L) ratio, percentage of extra large kernels (ELK), and arginine maturity index (AMI). Application of SADH in 1981 reduced the linoleic acid percentage and IV and increased the oleic acid percentage and O/L ratio. In 1982, SADH application led to significantly lower linoleic acid percentage and IV in all cultivars except VA 81B, and significantly increased the O/L ratio for Florigiant, NC 7, and NC 8C. Similar O/L changes were not significant for NC 6 and VA 81B. NC 7 had the greatest number of significant changes in composition percentages with decreases in palmitic, linoleic, arachidic, eicosenoic, behenic, and lignoceric acids, and an increase in oleic acid in seed of plants treated with SADH. The AMI values were lower for all cultivars and ELK percentage was higher for Florigiant and NC 6, indicating more mature seed, with SADH treatment. Thus, from the results of this 2-yr study, the application of SADH to reduce foliage growth also affected the ELK, AMI, and fatty acid distribution of seed from several peanut cultivars.