We studied 21 filgrastim (G-CSF)-mobilized peripheral blood stem cells (PBSC) apheresis products obtained from seven patients, and stored at 4 degrees C for periods of up to 96 hr prior to their reinfusion, to rescue high-dose chemotherapy. The apheresis products contained a median of 106 x 10(8)/L mononuclear cells (MNC), 14.6% of them displaying the CD34 antigen; the viability was over 90% in all samples studied at 24, 48, and 72 hr after harvesting. These PBSC were successfully used to rescue high-dose chemotherapy; patients received a median of 4.8 x 10(8)/Kg MNC; the median time to achieve > 500 granulocytes was 14 days (range 11-26) and the median time to achieve > 20,000 platelets was 20 days (range 11-40). Since autologous transplants with nonfrozen PBSC are feasible and less costly than those using frozen PBSC, restrictions to PBSC autotransplant programs may be overcome and costs may be diminished.