Xylopia papuana Diels (family Annonaceae), a large tree of the New Guinea rain forest, gives strongly positive tests for alkaloids, and an examination has now been made of both leaf and bark alkaloids. Another species, X. discreta (L. fil.) Sprague & Hutchins, has previously been studied and shown to contain the aporphine alkaloid, (-)-xylopine (I), together with alkaloids of the protoberberine type. Of the latter group, discretamine and discretinine afforded (-)-tetrahydropalmatine on methylation with diazomethane, and xylopinine was identified as (-)-norcoralydine. Apart from the common occurrence of (-)-xylopine there is, however, little resemblance between the alkaloids of X. discreta and X. papuana. No alkaloids of the protoberberine type have been obtained from either leaves or bark of X. papuana, which contain alkaloids of the aporphine and 1-benzyl-l,2,3,4-tetrahydroisoquinoline groups. 1-Benzyl-1,2,3,4-tetrahydroisoquinoline alkaloids predominate in the bark alkaloids and (+)-coclaurine (II) comprises approximately 50% of the total bases. (+)-Reticuline (III) is also present and (-)-xylopine is only a relatively minor constituent. The major alkaloids from the leaves are the aporphine alkaloids (+)-laurolitsine (IV) (approximately 50% of the total), (-)-roemerine (Va) (20%), and (-) anonaine (Vb) (20%). Only traces of coclaurine and reticuline could be detected in the leaf alkaloids.