We have isolated from a methanolic extract of the leaves of Mitragyna speciosa Korth a number of alkaloids, three of which (speciophylline, speciogynine, paynantheine) are newly described. The picrates of ether-extracted crude bases yielded mitragynine, corynantheidine, isomitraphylline, and the new speciophylline (an oxindole alkaloid structurally similar to mitraphylline, with a methoxy group position above the oxindole ring inferred from NMR). The picrate mother liquors yielded ajmalicine, the new speciogynine (an indole isomer of mitragynine) and paynantheine (a 9-methoxy corynantheine-type indole, the first such compound reported), plus unidentified alkaloids. Ether-insoluble bases mainly contained mitraphylline. Known alkaloids (mitraphylline, isomitraphylline, ajmalicine, corynantheidine) were identified by comparing m.p., mixed m.p., [α]D, hRf (thin-layer chromatography), ultraviolet, infrared, and NMR spectra with authentic samples. Speciogynine and paynantheine were confirmed as indoles via colour tests, UV, IR, and NMR. Their structures—including trans C/H junction for both, 9-methoxy groups (evidenced by aromatic proton splitting and methoxy singlets in NMR), and paynantheine’s olefinic multiplets matching corynantheine’s vinyl signals—were deduced from elemental analysis, equivalent weight, and spectral data.