The mouse embryonal carcinoma cell line F9 differentiates into parietal endoderm cells after a 3-day exposure to retinoic acid and dibutyryl cyclic AMP. Using the experimental metastases assay, we investigated the organ colonization properties of RA-treated and -untreated populations of F9 cells. The results show that untreated F9 cells colonize the liver with a high degree of specificity while the treated populations colonize the lungs. Cells derived from a lung colony colonized only the liver unless they were treated with RA. However, removal of the inducer from culture of differentiated cells did not cause reversal of the lung colonization potential. Our observations also indicate that it is unlikely that lung colonization is due to cell aggregation or to interaction between differentiated and undifferentiated cells. Taken together, these results suggest that RA induces the observed change of organ colonization properties of F9 cells.