The applicability of in vitro autoradiography, using 3H-thymidine, was tested on material obtained from gynaecological abrasion. Included were 161 abrasion samples obtained from 151 patients, and 88 per cent of them proved evaluable by autoradiography. The use of in vitro autoradiography was found to give no additional gain in information for biological assessment. Index testing by means of in vitro autoradiography failed to prove worthwhile unless it came to examination of polyps or of glandular-cystic hyperplasia or of effects exerted on the endometrium by ovarian tumours with sizeable hormonal activity. Endometrium was found to be a kind of tissue characterised in both intact and pathological condition by pronounced individual age-dependent and cycledependent variations of its marking indices.