Because we were interested in the phytochemical difference between Clausena and Murraya species (the latter contain only carbazole alkaloids but no coumarins), we studied the constituents of stem bark from Clausena excavata (Rutaceae) collected in Singapore. The acetone extract was fractionated by silica gel column chromatography and preparative TLC to isolate fourteen carbazole alkaloids and one coumarin, including seven new carbazole alkaloids (named clauszoline-A to G) and one new coumarin (5-geranyloxy-7-hydroxycoumarin). The structures of these new compounds were elucidated by means of spectral methods including high-resolution mass spectrometry (HR-MS), ultraviolet (UV) spectroscopy, infrared (IR) spectroscopy, proton nuclear magnetic resonance (1H-NMR) spectroscopy, nuclear Overhauser effect (NOE) experiments, and 1H-detected heteronuclear multiple bond connectivity (HMBC) experiments.