We examined the relative significance of hysteroscopic and ultrasonographic evidence of endometrial atrophy in relation to insufficient sample on outpatient endometrial biopsy in women with abnormal uterine bleeding. Multivariate logistic regression modelling was used to evaluate the independent effects of age, menopausal status, hysteroscopic findings and sonographic endometrial thickness on outpatient endometrial sampling (sufficient or insufficient) used as the binary dependent variable. Insufficient sample on endometrial biopsy was associated with hysteroscopic finding of endometrial atrophy (OR 4.79, 95% CI 1.05–21.91, P= 0.04) and sonographic endometrial thickness below 5 mm (OR 0.19, 95% CI 0.07–0.53, P= 0.001). There was no association with patient's age and menopausal status. In conclusion, when reassuring women with insufficient sample on outpatient endometrial biopsy, one can be confident about absence of pathology provided the hysteroscopic and sonographic endometrial assessment is consistent with endometrial atrophy.