OBJECTIVE To review the literature on the clinical activity and toxic effects of paclitaxel (Taxol). METHODS Results of phase I and II trials of Taxol in patients with various types of tumors are provided. METHODS Taxol is the first drug in a new class of antineoplastic agents known as the taxanes. These drugs demonstrate a novel mechanism of action characterized by promotion of the assembly of microtubules and stabilization of the tubules against depolymerization, resulting in mitotic arrest. RESULTS Numerous phase I and phase II trials have demonstrated the efficacy of Taxol in refractory ovarian carcinoma, breast carcinoma, lung cancer, head and neck cancer, and lymphoma. Various durations of infusions of Taxol have been used in several studies. In the treatment of most patients with ovarian cancer, Taxol can probably be administered by either short infusion or 24-hour infusion with no compromise in antitumor effect. Neutropenia seems to be less common when 3-hour infusions are used. Additional phase II trials are currently in progress, as are combination chemotherapy trials. CONCLUSIONS Taxol has definite antitumor activity in advanced ovarian and breast cancers and seems to have activity in lung cancer. Further clinical trials will determine the spectrum of activity of Taxol in other malignant tumors and define its role in combination chemotherapy for sensitive tumor types.