A new, highly productive source of maytansine and other maytansinoids has been found in the seeds of Maytenus rothiana (Walp.) Lobreau-Callen, a small upland tree of the Western Indian Ghats near Bombay. From this source, a greatly improved and commercially feasible preparative liquid chromatography isolation procedure has been designed. Also, in an off-season collection, the wood of Maytenus phyllanthoides Benth (M. texana (Benth) Lundell) from the southern Texas Gulf coast has been found to contain only a very small amount of maytansine. In a later collection, no maytansinoids were found in the fruit.