Abstract： Objective To evaluate the efficacy of mini- invasive percutaneous nephrolithotomy (MPCNL) in treatment of severe spinal deformity with upper urinary tract calculi.Methods Between August 2001 and February 2010,10 patients with severe spinal deformity(Cobb＞90°) combined and upper urinary tract calculi (a total of 11 side kidneys) underwent ultrasound-guided MPCNL in our hospital.The postoperation hemorrhage and the injury of neighboring organs were observed before and after operation.Furthermore,the mean operation time and the decrease level of hemoglobin at 48 h after operation were recorded.The abdomen film and ultrasound were used to reexamine the removal of upper urinary tract calculi after operation.Follow-up was carried out in thcse patients,the time and recurrence of calculi were recorded.Results A total of 14 MPCNLs were performed in 11 side kidneys,including 10 times of single channel MPCNL and 4 times of double channel MPCNL.All the operations were successful with no complications such as hemorrhage or neighboring organ injury during and after operations.The mean operation time was (96±38) min,and the decrease of hemoglobin was (16±7) g/L at 48 h after operations.In postoperative reexamination,the abdomcn film and ultrasound showed that 1 l side upper urinary tract calculus were totally removed.In the iollow-up of (36±28) months,tthe recurreuce of lower caliceal stone was found in 1 case and no recurrence in the remaining 9 cases.Conclusion Ultrasound-guided MPCNL is safe and effective in treatment of severe spinal deformity with upper urinary tract calculi.