© 2022 Informa UK Limited, trading as Taylor & Francis Group.We aimed to evaluate ultrasonography (US), colour Doppler US (CDUS) and sonoelastography (SEL) findings of histopathologically proven abdominal wall scar endometriosis in comparison with menstrual phases. A total of 24 female patients with scar endometriosis were included. Lesion size, volume, echogenicity, solid/cystic or complex appearance, contour and location on US, vascularisation on CDUS, and elasticity on SEL were recorded in both menstrual and ovulatory phases. Hypoechoic heterogeneous lesions with increased peripheral echogenicity were observed in all lesions. The mean ± standard deviation (SD) volume of the lesions in the menstrual and ovulatory phases of the lesions was 4.36 ± 3.01 cm3 and 4.63 ± 7.61 cm3 (p =.316). The mean ± SD resistive index values on CDUS in the menstrual and ovulatory phases were 0.96 ± 0.09 and 0.97 ± 0.07, respectively (p =.667). The SEL examination demonstrated a hard coding pattern in all cases with no statistically significant difference between menstrual and ovulatory phases (p =.176). We found no significant difference in terms of US, CDUS and SEL findings of scar endometriosis in comparison with menstrual phases which suggests there is no need to evaluate the patient in a specific menstrual phase.Impact StatementWhat is already known on this subject? Scar endometriosis is the endometriosis located at the abdominal wall around the scar area with a very rare incidence. The typical sonographic findings of scar endometriosis are a hypoechoic solid mass with irregular contours. High resistive index on colour Doppler ultrasonography (CDUS) and hard coding pattern on sonoelastography (SEL) are seen in the lesion. Whatdothe results of this study add? This is the first study that evaluates sonographic features of scar endometriosis lesions in the menstrual phase. We found that scar endometriosis lesions did not have a significant difference in terms of B-mode US, CDUS and SEL in menstrual and ovulatory phases. Whatarethe implicationsof these findings for clinical practice and/or further research? Our findings suggest that there is no need to evaluate the patient in a specific menstrual phase.