Sweet potato (Ipomoea batatas (1.) Lam., 'Georgia Jet') plants were grown in open field plots and open top chambers at C02 concentrations of 354, 431, 506, and 659 µll-1 during May to August, 1984. The plants were harvested at 92 days of growth and the different plant parts were separated. The number of tubers per plant increased significantly with an increase in CO2 concentrations. However, the density, volume, and mean length of US #1, 2, canner, cull or jumbo roots did not show any significant differences with elevated C02 concentrations. Starch content in sweet potato roots increased significantly in plants grown at 431 and 506 µll-1 COZ. The percentage of sucrose, soluble amino acids, and proteins decreased with an increase in C02 enrichment and were most noticeable at 659 µll-1 C02 atmosphere.