Three categories of skin from Hanford miniature swine were examined microscopically: normal, unfrozen skin; skin exposed to -75 degrees C air for 5 min, 6 h postinjury; and skin frozen postmortem. Frostbitten skin (antemortem freezing) was characterized grossly by a purple discoloration and microscopically by dilated, blood-filled, superficial capillaries. Other changes in the frostbitten skin were vacuolated epithelial cells and dermal edema. Unfrozen skin (controls) and skin frozen postmortem were more difficult to differentiate. However, the epidermis of the latter usually was compressed and more basophilic. We concluded that skin frozen antemortem could be separated from skin frozen postmortem by its intense hyperemia, characterized grossly as a purple discoloration and microscopically by engorged capillaries.