Three new limonoids, limonophyllines A-C (1, 4 and 5), along with two known limonoids (2 and 3) and 11 acridone alkaloids (6-16) were isolated from the stems of Atalantia monophylla. All isolates were evaluated against cholangiocarcinoma, KKU-M156, and HepG2 cancer cell lines. Compounds 12, 14 and 16 displayed cytotoxicity against KKU-M156 cell line with IC50 ranging from 3.39 to 4.1 μg/mL while cytotoxicity against HepG2 cell line with IC50 ranging from 1.43 to 8.4 μg/mL. The structures of all isolated compounds were established by spectroscopic methods including 1D and 2D NMR, IR and mass spectrometry.