A study was carried out to identify Leucaena accessions best adapted to a semi-humid lowland tropical environment of East Africa. Six Leucaena leucocephala accessions and five Leucaena species were evaluated for growth and biomass production in comparison with L. leucocephala K28, a cultivar widely distributed locally. Approximately 32 weeks after transplanting 6-week-old Leucaena seedlings, accession No. 368 was the tallest (4.4 m), had the thickest stems (diameter 30 mm at 0.3 m above the ground), had the second highest number of branches per plant (35), and produced most forage dry matter (DM, 9.0 t ha-1) and air-dried wood (26.9 t ha-1). Leucaena leucocephala K28 was ranked second for all parameters except the number of branches for which it ranked first. Based on the cumulative production from five subsequent 8- to 12-week harvests, accession No. 71 ranked first for yields of forage DM and air-dried wood (12.7 t ha-1 and 9.5 t ha-1, respectively). Despite forage DM yields ranging from 8.7 to 12.7 t ha-1, cumulative yields were not significantly different among accessions. None of the accessions performed significantly better than cultivar K28 for growth and biomass production and, therefore, it remains currently the recommended cultivar. Of the five Leucaena species studied, L. leucocephala had the best performance followed by L diversifolia.