The modified chick chorioallantoic membrane assay was used to measure the angiogenic activity of whole human endometrium, endometrial gland and endometrial stromal cell preparations. Specimens were studied from normal subjects and from those suffering from dysfunctional uterine bleeding. This was done in order to investigate possible sites of angiogenic factor synthesis in endometrium. Significant angiogenic activity was demonstrated in all three sites and was present in all phases of the cycle except for the late secretory phase specimens. In the late secretory phase, compared to the controls, there was no significant angiogenic activity in the whole endometrial, endometrial gland nor endometrial stromal cell preparations. There were no differences in angiogenic activities between the various phases studied apart from a significant decrease in angiogenic activity for the endometrial gland cell preparations between the midsecretory phase and the late secretory phase. This study suggests than human endometrium produces local angiogenic factors throughout the menstrual cycle and that these factors may decrease towards the end of the cycle. It has been suggested that dysfunctional uterine bleeding may be due to disturbances in local angiogenic factors produced in the endometrium. This study found no significant differences in angiogenic activities between normal endometrium and dysfunctional endometrium. This suggests that dysfunctional uterine bleeding may not be due to disturbances in local angiogenic factors.