background: This work was intended to distinguish the results of Percutaneous Nephrolithotomy (PCNL) related to stone–free rates (SFR) by the varying body mass index (BMI) of the patients who subjected for lower calyx stone treatment (with a stone range of ≥2 cm). Materials and methods: A total of 287 patients who went through the PCNL for kidney stones were selected for the study. Only patients treated at Shahid–Ghazi Hariri Surgical Specialties Hospital (Medical City) and Al–Qima Private Hospital (Baghdad) within the time frame of January 2015 to April 2018 selected for the study. Information on patients’ BMI and SFR was collected and analyzed to compare and contrast the differences in obese patients. Results: The average age and BMI of the patients are 41 years old and 34kg/m2 respectively. For total mean stone size 2.2 cm. Besides that, the average value for height was 173cm and weight 101kg. The overall stone–free rate was 82% and the mean hospital stay was 115±51.21 min, Major complications were seen in 65 patients (22.6%). No statistically significant differences were found in SFR, age and stone side among the four groups. The stone–free rates (SFRs) of a single procedure for the groups were 85%, 79.3%, 79%, and 84%, respectively. Major complications were not observed either during or after the operations. Conclusion: The effectiveness of PCNL treatment for removal of lower calyceal stone is influenced by the varying patients’ BMI value and results in high SFR value.