Purpose: To evaluate morbidity and oncological outcome in a multicentre series of women with gynaecological malignancies infiltrating pelvic side wall (PSW) that received laterally extended pelvic resection (LEPR). Methods: Patients operated between 2007 and 2017 at three institutions were included. LEPR was defined as an en bloc lateral resection of a pelvic tumour involving sidewall muscle, and/or bone, and/or major nerve, and/or major vascular structure. Postsurgical complications and survivals were evaluated. Results: Sixty-three women with gynaecological tumours involving PSW were treated with LEPR. Five women underwent primary LEPR, whereas 58 (92%) patients needed LEPR because of recurrence. Twenty-four women (38%) received previous radiation therapy before the surgery. R0 resection was achieved in 54 patients (85.7%), whereas the pathologic margins were microscopically and macroscopically positive in 8 (12.7%) patients and 1 (1.6%) patient, respectively. There was one perioperative death, whereas major postoperative complications occurred in 17 patients (27.7%). Thirty (47.5%) women experienced recurrences: 24/54 (44.4%) were in the R0 group, and 6/9 (66.6%) were in the R1 group, with a median PFS of 15 months and 7 months, respectively (p = 0.024). In total, 11 of 54 (20.3%) patients died of disease in the R0 group and 5 of 9 (55.5%) in the R1 group; a median OS was not reached and was 32 months for R0 and R1 groups, respectively (p = 0.033). Conclusions: Involvement of the PSW should not prevent obtaining R0 resection. Although the LEPR is associated with considerable morbidity (≈ 30%), a long-term survival seems to be achieved in those women with complete resection.