Six new diterpenoids, caucanolides A−F (1−6), have been isolated from extracts of the gorgonian octocoral Pseudopterogorgia bipinnata collected near the Colombian Southwestern Caribbean Sea. The structures of 1−6 were elucidated by comprehensive analysis of spectroscopic data. The caucanolides showed in vitro antiplasmodial activity against the malaria parasite, Plasmodium falciparum. In addition to possessing structures based on novel carbon skeletons, one of these metabolites, caucanolide B (2), constitutes the only example from nature of a secondary metabolite possessing the N1,N1-dimethyl-N2-acylformamidine functionality.