Summary Female mice were exposed to 500 ppm vinyl chloride (VC) for 6 h/day 5 days/week for 1–8 weeks. Groups of mice were killed at different times during this period. DNA damage, expressed as single-strand breaks (SSB), was studied in liver, kidneys, lungs, spleen and brain. The level of SSB increased in liver, kidneys, spleen and lungs with time of exposure and reached a plateau for kidneys and lungs after 80 and 120 h of exposure. In spleen there was only a slight increase in the SSB, and in brain no detectable increase was found.