Two new compounds, designated as itampolins A (1) and B (2) were isolated from the sponge Iotrochota purpurea collected at Itampolo, southwest of Tule´ar, Madagascar. The structures of the compounds were elucidated mainly on the basis of 1D and 2D NMR and mass spectroscopic data and, in the case of 1, also by chemical degradation.