Background Australian clinical guidelines recommend further investigation in females with postmenopausal bleeding (PMB) and endometrial thickness (ET) of ≥4 mm on transvaginal ultrasound (TVUS). However, the literature indicates that an ET of ≥3 mm as an upper limit is a more sensitive predictor of endometrial malignancy (EM) in females with PMB. Aims To assess whether Australian guidelines for PMB with an upper limit of 4 mm ET on ultrasound investigation, is sensitive enough for malignancy detection. Material and methods A retrospective study was performed on tissue results in PMB presentations to the Gold Coast Hospital and Health Service between 2011 and 2015. Results Twenty point nine percent of women with PMB had a malignancy. With an upper limit of 4 mm in ET on ultrasound, malignancy was present in 22% of participants. [Correction added on 10 July 2020, after first online publication: percentage of women with PMB that had a malignancy has been amended to twenty point nine percent.] CONCLUSIONS: A limit of 3 mm for ET in PMB, along with office endometrial biopsy, should be considered to ensure timely diagnoses.