Abstract Background Simultaneous retrograde and antegrade endoscopic combined intrarenal surgery in modified supine lithotomy positions offer significant progress in the endoscopic management of urolithiasis. The operative time has been significantly reduced. Aim of the Work To evaluate the Galdakao-modified Valdivia position in simultaneous handling of upper and lower urological pathologies in the same units. Patients and Methods The evaluation for the Galdakao-modified Valdivia position regarding the benefits in different upper and lower urological diseases was the aim of our prospective randomized clinical trial that will started on April 2017 and ended by April 2019. Results The study has included 60 patients comprising males and females. Conclusion We believe that GMSV provided a great versatility in the treatment for urolithiasis along the whole urinary tract, ante-retrograde access, treatment of uretero-ileal strictures in patients with urinary diversions or neobladders, missed double j stent, bilharizoma of the ureter and bladder mass involving the ureteric orifice. Also, the advantage provided by this approach to the surgeon, patient and anesthetist may lead to widespread adaptability of this technique in the management of complex urolithiasis.