The effects of treatment with colchicine, cytochalasin B, and low temperature (4 degrees C) on the metastatic behavior of the B16-F10 melanoma cell line were examined. The growth of metastases and the distribution of radiolabeled tumor cells were monitored in inbred C57/BL6 mice given iv injections of B16-F10 cells. Cells treated previously with both drugs, but not with low temperature, produced fewer lung nodules than did control cells and displayed alterations in tumor dissemination patterns. In vitro studies revealed that both drugs reduced the rate of adhesion of the tumor cells to bovine endothelial cell monolayers, the rate of migration from agarose droplets, the formation of homotypic aggregates, and agglutination by wheat germ agglutinin. The drugs also induced morphologic alterations of the cells grown in monolayer culture but had little effect on cell volume.