A 32P uptake test to diagnose an intraocular tumour was performed on a lactating woman. Breast feeding of her infant had been stopped and after injection of the 32P, a sample of breast milk on two consecutive days was collected. The concentration of 32P in the milk was greater in the second sample than the first, but it was calculated that the potential whole body radiation dose to her infant on the second day would not have exceeded 180 microSv (18 mrem).