The clinical outcomes of 2968 patients with active cancer receiving home nutrition support are described. Of these patients 1672 were receiving home parenteral nutrition and 1296 were receiving home enteral nutrition. The outcomes of these active cancer patients are compared to those of 123 radiation enteritis ("cured" cancer) and 480 Crohn's disease patients receiving home parenteral nutrition and 918 noncancer dysphagic patients receiving home enteral nutrition. This longitudinal clinical information was reported to the North American Home Parenteral and Enteral Nutrition Patient Registry between 1985 and 1990. Evidence indicates that the number of home parenteral and enteral nutrition patients has increased nationally by about 25% each year between 1989 and 1990. In a subsample of 37 home nutrition support programs that have consistently reported their data to the registry since 1985, more than 90% of their program growth was accounted for by new patients with active cancer. This is now the largest single diagnosis of patients starting home parenteral and enteral nutrition. The mean survival time of cancer patients is 6 months after starting home parenteral and enteral nutrition, but 25% live beyond a year and 20% resume full oral nutrition. Although most active cancer patients experience only partial rehabilitation, for those patients with longer survival, rehabilitation is more complete. The outcome is relatively better for children and for patients whose neoplasm is leukemia, lymphoma, small bowel, or liver. In comparison, 96% of home parenteral nutrition Crohn's patients, 80% of home parenteral nutrition radiation enteritis patients, and 60% of home enteral nutrition noncancer dysphagic patients survive at least 1 year. Adult active cancer home parenteral and enteral nutrition patients do not have a greater incidence of therapy-related readmissions than other patient groups, however, their overall rehospitalization rate is much more frequent. This article discusses factors that may have contributed to this growth in home nutrition support in active cancer patients. It attempts to clarify where this therapy is clearly justified and where more information is needed. It emphasizes some of the special issues that need to be addressed in treating these vulnerable patients.