We studied the alkaloid composition of Annona muricata L. (Annonaceae) leaves collected in February 2009 in Conakry Botanical Garden (Republic of Guinea). Ordinary CHCl3 extraction afforded total alkaloids (0.125%) that were separated into phenolic and nonphenolic parts. Column chromatography over silica gel of the nonphenolic fraction isolated three bases; of the phenolic fraction, one. Spectral data, physical constants of the alkaloids and their salts, chemical transformation, and comparison with authentic samples identified the pure alkaloids. Base 1 was identified as anonaine, Base 2 as isolaureline, Base 3 as xylopine, and Base 4 as coclaurine. Thus, we studied the alkaloid composition of Annona muricata leaves and isolated for the first time and identified the aporphine alkaloids anonaine, isolaureline, and xylopine and the benzyltetrahydroisoquinoline alkaloid coclaurine, which was isolated previously from this plant.