The optimal schedule for paclitaxel administration has not yet been determined. This phase I/II study was carried out to evaluate the safety of paclitaxel administration by 1-h infusion in the outpatient setting. A total of 43 patients with advanced pretreated malignancies (18 breast, 18 ovarian, and 7 non-small-cell lung cancers) received at least 2 cycles of paclitaxel given at 175 mg/ m2 in a single dose by 1-h i.v. infusion. This protocol was repeated every 21 days. All patients were premedicated as follows: promethazine given i.m. at 50 mg, dexamethasone given at 16 mg in 250 ml normal saline by i.v. infusion for 20 min and ranitidine given i.v. at 50 mg in 250 ml normal saline over 15 min, all premedication being carried out 1 h before the paclitaxel infusion. In a total of 156 cycles, only 1 patient presented with a hypersensitivity reaction (grade 2 urticaria in 1 cycle) and another patient developed transient facial flushing (in 1 cycle: this was resolved by slowing of the infusion rate) on this schedule of paclitaxel administration. Other adverse side effects were usually mild and well tolerated. Alopecia was universal; myelosuppression was uncommon because our patients were supported with granulocyte colony-stimulating factor (G-CSF, lenograstim) given at 34 IU/day in the presence of a neutrophil count of < 500 microliters; neutropenia was seen in 50/156 (32%) cycles and was mild. Neurotoxicity was the most serious adverse effect, and all patients experienced mild to severe neuro-muscular toxicity, mainly in the form of peripheral sensorimotor neuropathy and myalgias. In conclusion, 1-h paclitaxel administration is safe and reduces the duration of treatment, making its use more convenient and easy in the outpatient setting. A prospective comparison of 1-h versus 3-h paclitaxel infusion in terms of efficacy and toxicity is the subject of our current randomized study.