True metabolizable energy (TME) values of cassava tuber meal and cassava leaf meal were determined using 18 adult Single Comb White Leghorn roosters. Afters 24 h of fasting, 6 roosters were force-fed 25 g of each of these feedstuffs. Six roosters were fasted for another 48 h and served as negative controls. Excreta were collected for 2 consecutive 24 h periods. Length of collection period had no effect on the TME value of cassava tuber meal, indicating that a 24 h collection period time was adequate. A collection period of ? 48 h, however, was required for roosters force-fed cassava leaf meal. The mean TME values (dry basis) of cassava tuber meal and cassava leaf meal were determined to be 15.73 ± 0.25 and 8.33 ± 1.17 MJ kg-1, respectively.