The vinca alkaloids represent one of the oldest classes of antineoplastic agents used in humans with a wide spectrum of activity against both animal and human tumors. These agents are known to inhibit microtubule polymerization. Vinorelbine is a semisynthetic analog that reached Clinical Trial on the basis of less preclinical evidence of toxicity to neuronal tissue and greater cytotoxic activity in preclinical models than the older compounds of this class. In humans, the clearance of this agent shows a wide variation among subjects with the predominant toxicity being hematological. Significant antitumor activity has been observed in diseases that previously have been shown to respond to vinca alkaloids.