Two experiments were conducted, (1) to determine the effect of the polyphenol content of sorghum on nitrogen and energy digestibility and (2)to compare a high polyphenol content class KF sorghum cultivar (BPS)and a low polyphenol content class KM cultivar (NS) with maize (MM) as grain components in pig growth diets formulated to be equal in DE and lysine content. BPS had a negative effect on dietary nitrogen digestibility when compared to NS. Nitrogen retention when expressed as a percentage of digested nitrogen was however slightly higher for a BPSthan for a NS-containing diet (54 % vs 49 %). Although paraformaldehyde treatment had an advantageous effect on nitrogen digestibility, nitrogen retention was adversely influenced. Although the DE content of the BPS cultivars was generally lower than that of NS, DE content of the BPS was substantially increased by reducing its polyphenol content with paraformaldehyde treatment. Pigs fed NS had live mass gains between 2 and 13% higher than BPS-fed pigs, and 4 to 6 % higher than pigs fed maize based diets. Pigs fed the maize containing diets were however the most efficient utilizers of dietary DE, 2 to 4 % better than NS-fed pigs and 7 to 12% better than BPS-fed pigs.