Data presented in this report describe countercurrent centrifugal elutriation (CCE) recovery profiles of hematopoietic colony-forming cells (CFC) in marrow from normal and 5-fluorouracil-(5-FU) treated mice. Of the total nucleated cells, 75%-95% were recovered, and up to 80% of CFC were recovered after CCE of bone marrow from normal mice. Red blood cells and the majority of lymphocytes were collected in fractions well separated from the CFC. In addition, the CCE recovery profiles of populations of CFC (i.e., BFU-E, CFU-E, GM-CFC, and HPP-CFC) were distinct. The distribution of recovered day 8 CFU-S was different from the distribution of day 12 CFU-S. The CCE recovery profiles of CFC in regenerating marrow from 5-FU-treated mice were shifted to fractions of larger cells, presumably in cell cycle. These data demonstrate that CCE is useful as a method of further characterizing qualitative and quantitative changes in populations of CFC occurring after various hematopoietic-influencing regimens.