Four murine cellular tumor models expressing various combinations of oncogenes (SV40 large T and v-Ha-ras, SV40 large T and v-src, SV40 large T and neu, adenovirus EIA and v-Ha-ras) induce sarcoma when they are inoculated s.c. into the DBA/2 syngenic mice. The metastatic patterns, distribution and fate of these tumor cells transplanted by two different routes into syngenic DBA/2 mice have been studied. All the tumor cell lines except EIA-ras, induce massive overt artificial metastases principally in the lung after i.v. injection. In s.c. tumor-bearing mice, a few resting cells colonize the lung as micrometastases. When removed from this tissue context and injected s.c. these cells regain their proliferative potential and grow as local tumors which again give rise to occult pulmonary micrometastases.