Summary, A comprehensive study of the scientific literature regarding tin content in normal and pathogenii; himiiin tissue has disclosed that various organotin materials retard both the onset and growth of cancer in laboratory animals, and decreased tissue tin in humans may be associated with lumour development.Initial studies by the authors have shown that the thymus gland of the mouse possesses a relatively high concentr;ition of tin and is also the major site of accumulation for I'C-labelied tri-n-biityltin fluoride (TBTF), When mammary cancer-prone mice with transplanted tumours were orally dosed continuously with this agent in their drinking water, the tumour growth rate was significantly reduced. Both mouse mammary tumours and human lung tumours show low tin contenl compared to normal body tissue.