Three new carbazole alkaloids, mukoenigatin (1), bikoeniquinonine (2) and murrayadinal (3), were isolated from the aerial parts of Murraya koenigii, along with mukeonine-B (4). Their molecular structures were determined on the basis of spectral analysis including UV, IR, MS, and 2D NMR spectroscopy. The antimicrobial activity of different fractions of plant extract was also determined.