Paclitaxel is an antineoplastic agent derived from the bark of the Pacific Yew, Taxus brevifolia. The origin of the agent had severely limited availability. The needles of the European Yew, a renewable source, provide the precursor of docetaxel, which is extracted, for further modification. In some tumor systems, docetaxel has a superior in vivo activity when compared to paclitaxel; Docetaxel acts by inducing polymerization of tubulin to form microtubules that remain stable, resulting in subtle toxicity in the G2 or M phase of cell division. As an inhibitor of cell replication, docetaxel is 2.5 times more potent than paclitaxel in J774.2 and P388 cells and at least fivefold more potent in paclitaxel-resistant cells. This phase II study will study the response rate to docetaxel in various strata of recurrent solid tumors of childhood, and further assess the toxicity of docetaxel in a larger group of pediatric patients treated at the current defined maximum tolerated dose.