Four new alkaloids, (−)-8′-oxo-agelasine D (2), ageloxime B (3), (+)-2-oxo-agelasidine C (4), and 4-bromo-N-(butoxymethyl)-1H-pyrrole-2-carboxamide (5), and the known compound (−)-ageloxime D (1) were isolated from the marine sponge Agelas mauritiana. Their chemical structures were established on the basis of spectroscopic analysis. Compounds 1and 3both showed antifungal activity against Cryptococcus neoformansand antileishmanial activity against Leishmania donovani in vitro. Compound 3also exhibited antibacterial activity against Staphylococcus aureusand methicillin-resistant S. aureusin vitro.