The temporal and spatial parameters of oestrogen-induced increases in RNA, protein and DNA synthesis were investigated autoradiographically in mice undergoing experimental diapause. The tritiated precursors, uridine, amino acid hydrolysate and thymide, were instilled into uterine lumen for a 15 minute pulse at various times after subcutaneous oestrogen treatment. RNA synthesis increased between 15 and 30 minutes, and protein synthesis between 30 and 45 minutes, after oestrogen administration. DNA synthesis did not increase up to 24 hours after oestorgen. No spatial correlations could be made between trophoblastic giant cell transformation and the RNA and protein synthesis although both are induced by oestrogen.