Two experiments to evaluate ranges of weight of seed setts of yam (Dioscorea rotundata, Poir) cv Black Guinea were established in a Typic Hapludults soil in Corozal in the central hill lands of Puerto Rico in 2004 and 2005. The planting distance for both experiments was 30.4 cm by 1.2 m. Treatments in the first experiment were sprouted and non-sprouted seed setts of 42- to 70-g, 71- to 98-g, and 99- to 126-g weight ranges. In the second experiment only non-sprouted seed setts of 42- to 70-g, 71- to 98-g, and 99- to 126-g and 127- to 156-g weight ranges were evaluated. In the first experiment, the average yield of commercial yams ranged from 17.3 mt/ha to 33.7 mt/ha. In the second experiment, the average yield of commercial tubers ranged from 9.96 mt/ha to 20.79 mt/ha. In the first experiment, non-sprouted seed setts yielded more than the seed setts that had six weeks to sprout in a shadehouse before field planting. No differences in commercial yield were found among the non-sprouted seed sett ranges. Therefore, the lighter seed sett range of 42 to 70 g should be used for planting. In the second experiment, no differences in yield were found among the 71- to 98-g, 99- to 126-g and 127- to 156-g ranges. Results indicate that seed setts used for planting should be of the 71 -to 98-g seed sett range. Results of both experiments indicate that a seed sett range of 42- to 98-g should be used for planting.