The relationship between the pattern of pulsatile LH release and the response to oestrogen provocation was studied in twenty amenorrhoeic or oligomenorrhoeic subjects. In 12 subjects with positive oestrogen-gonadotrophin feedback a definite pulsatile pattern of LH release was demonstrated with a pulse frequency of 60--80 min and an increase from nadir to peak ranging between 30 and 58%. The mean basal LH concentration was significantly higher in this group (P less than 0.001). Of eight subjects who had absence of positive feedback, five showed infrequent pulses, 1--2 during the four-hour period. These were of low amplitude and with a percentage increase of 45--70 from nadir to peak. The remaining three did not have a pulsatile pattern of LH release. Positive feedback, as demonstrated by an oestrogen provocation test was thus found only in patient having 3 or more LH pulses in the 4 h study period; an LH pulse frequency similar to that in the early follicular phase in regularly menstruating women.