The extractable iron and total iron were determined in experimental, subcutaneous hematomas (5 ml blood) of rats after different periods of vital time. The extractable iron was determined from homogenate extract obtained after 24-h incubation with concentrated HCl diluted 1:3 and protein precipitation. For the determination of total iron, the specimens were wet-ashed. The same iron determinations were also made for the corresponding control specimens of the subcutaneous tissue. Extractable iron started to rise over the control values in 2-day-old hematomas, being about 5 times higher after 3 days, about 15 times higher after 7 days, and about 20 times higher after 14 days. The ratio of extractable iron and total iron expressed as percentages was about 1% in 1-h and in 1-day-old hematomas, about 20% in 3-day-old hematomas, about 50% in 7-day-old hematomas, and about 65% in 14-day-old or older hematomas. The effect of autolysis for 3 days at room temperature was studied on 1-h-old hematomas. Extractable iron values were slightly higher in the autolyzed specimens, but the difference was statistically insignificant as compared to specimens taken immediately after death.