SYNOPSIS. Trypanosoma (Megatrypanum) megachiropterorum sp. n. from the flying fox, Pteropus tonganus Quoy & Gaimard, from the Kingdom of Tonga, is described. The trypomastigotes measure 32 ± 1.74 (here and below S.D.) (27–37.5) × 3.6 ± 0.23 (3–4.5) μm and has a flagellum averaging in length 6.4 ± 0.92 (4.5–10) μm. Their nuclear index is 1.2 ± 0.16 (0.7–1.6) and their kinetoplastic index equals 6.2 ± 0.32 (5.5–7.1). This is the first report of a member of the subgenus Megatrypanum from bats outside the American and African continents and also the first record of a trypanosome from bats in the Pacific area. Copyright © 1979, Wiley Blackwell. All rights reserved