Docetaxel, a promising inhibitor of microtubule depolymerization has shown significant anti-cancer activity during phase I and early phase II trials. The recommended dosage for phase II trials is 100 mg/m2 every 3 weeks which provides optimal activity with tolerable adverse effects. Docetaxel has shown high single agent activity including use as first- or second-line therapy and in anthracycline refractory breast cancer patients. Results have been comparable to that of established treatments for breast cancer. In addition, docetaxel has shown significant activity in non-small cell lung cancer and a range of other tumors, but no activity in renal or colo-rectal tumors. At present it is undergoing further evaluation in combination therapy. The safety profile of docetaxel is well defined. Major adverse effects include hypersensitivity reactions, fluid retention and neutropenia. Peripheral neuropathy is not a significant adverse effect. The aims of phase II trials with regard to counteracting side-effects are therefore 2-fold: firstly, to evaluate the use of premedication with corticosteroids and antihistamines as a means of counteracting hypersensitivity reactions and fluid retention; secondly, to determine whether granulocyte colony stimulating factor may be useful for attenuating neutropenia.