Structural studies on the six alkaloids isolated from Tylophora crebriflora (N. O. Asclepiadacease) are described here. Spectral data indicate that five of these alkaloids (A‐E) possess the dibenzo[f, h]‐pyrrolo[1,2b]isoquinoline skeleton known to be present in tylocrebrine. They differ in the number, nature, and distribution of the oxygen‐bearing substiuents and in the presence or absence of a benzylic‐type hydroxyl. An oxygen substitution pattern of 3, 4, 6, and 7 is suggested for Alkaloids A, B, and C and that of 2, 3, 4, 6, and 7 for Alkaloids D and E. Alkaloid F is shown to be a seco analog of tylocrebrine with a 1,2‐diphenyl cis stilbene skeleton. Copyright © 1970 Wiley‐Liss, Inc., A Wiley Company