85Sr uptake and ash-weights of the fracture callus of the tibia and of a heterotopic tibia graft in the same animal were measured in mice and followed up to 30 days after grafting and fracture. Growth and uptake of 85Sr was higher in the callus compared to the graft and reached a maximum at about 17 days post fracture. After this period 85Sr uptake of the callus decreased rapidly, whereas in the graft an initial increase of 85Sr uptake was followed by a slow decline after 17 days. Ash-weights of the grafts increased slightly up to day 11 und remained constant thereafter. A low 85Sr uptake of the uninjured tibia between days 2 and 4 post fracture compared to the data of the following period was assumed to be due to a transitory enhanced excretion of 85Sr along with Ca during this early period. Between 9 and 30 days the 85Sr uptake of the uninjured tibia remained unchanged. An influence of fracture repair or graft healing on the mineral uptake of the whole skeleton therefore cannot be confirmed by our data.