Radiation damage associated with grown-in dislocations in crystals which have been irradiated with neutrons between 200 and 400°C is described. It is proposed that point defects precipitate near climbing grown-in dislocations because the capacity of these dislocations to absorb point defects is limited by the rate at which jogs can be nucleated. This limitation is likely to be important only in the early stages of damage formation when the total line length of dislocation in the crystal is low.