Romucosine (1), a novel aporphinoid alkaloid possessing a N-(methoxycarbonyl) group, along with 12 known compounds including eight isoquinoline alkaloids, anonaine (2), glaucine, purpureine, liriodenine, oxoglaucine, oxopurpureine, berberine, and tetrahydroberberine, and four lignans, yangambin, magnolin, eudesmin, and membrin, have been isolated and characterized from the fresh unripe fruits of Rollinia mucosa (Annonaceae). The structure of 1 was established by chemical and spectroscopic means.