Contraceptive implants are subdermal capsules that release progestins over a 3 year period. The most common and frequent side effect of implants is abnormal uterine bleeding (AUB). Various diagnostic techniques are available to determine the cause of AUB. However, there have only been a few studies investigating endometrial pathology experienced by implant contraceptive acceptors. The aim of this study is to investigate endometrial etiologies of abnormal uterine bleeding on single-rod implant contraceptive acceptors. This observational descriptive study using cross sectional method was performed on acceptors of Monoplant® single rod implant containing 160 mg of Levonorgestrel who had abnormal uterine bleeding. A total of 20 subjects was recruited to the study. Women with cervical cancer, cervical stenosis, pelvic inflammatory disease, or abnormal uterus morphology were excluded. All the participants of the study had their endometrium assessed with a transvaginal ultrasound, hysteroscopy, and histopathology of an endometrial biopsy. Assessment of endometrium revealed that endometrial thinning and endometrial atrophy were found on 78.9% of subjects. Results of transvaginal ultrasound and hysteroscopy were compared to histopathologic results. Endometrial thinning and atrophy were found in majority of single rod implant acceptors having abnormal uterine bleeding. However, further examinations should be performed to eliminate additional etiologies.