Intravesical instillations of ADM have local and systemic effects: Locally a chemocystitis can be seen with a frequency of 10 - 40%. It can usually be treated conservatively and only rarely the therapy has to be discontinued. Urothelial dysplasia, proliferation and - in rats - the development of epithelial bladder tumors following repeated instillation need further investigations. ADM is absorbed mainly by exophytic tumors with a large surface area and changes in membrane characteristics and - less - by the normal urothelium and solid tumors. Whether the local cellular uptake of ADM can be enhanced by the use of adjuvant substances such as surfactants, enzymes or detergents is presently subject of animal investigations (Engelmann 1984). Systemically neither in animal studies nor in investigations in humans relevant concentrations are detected so that untoward side effects like cardiotoxicity will not occur. The increase in absorption that has been documented due to TUR or cystitis does not lead to a clinically significant rise of serum concentrations.