Two new imidazole alkaloids were isolated from a Micronesian sponge, Leucetta sp. Kealiiquinone (2) is a naphthoquinone which appears to be biogenetically derived from 1, which is a dibenzyl-substituted imidazole. Pyronaamidine (1) is cytotoxic against KB cells, MIC = 5 ng/mL. © 1990, American Chemical Society. All rights reserved.