Transformed organ cultures of Withania somnifera were established following infection with wild type nopaline and octopine strains of Agrobacterium tumefaciens. The oncogenic strains had different levels of virulence on two genotypes studied, the main difference was found in the nature of the galls formed and in their subsequent morphological competence. Ten percent of the galls obtained following infection with nopaline strain N2/73 spontaneously developed shooty teratomas of altered phenotype. The shooty teratomas grew in unsupplemented basal medium and were able to synthesize both the major withanolides of the parent plants. Withanolide synthesis in shooty teratomas was much higher (0.07-0.1% withaferin A and 0.085-0.025% withanolide D) than in non-transformed shoot cultures.