Despite the benefits of spinal anesthesia and the preference of anesthesiologists for this technique, it is less accepted by urologists due to the proximity of the stone place in the ureter and the possibility of pain, restlessness, and occasional movements of the patient during surgery. The current study investigated the success of bupivacaine plus intrathecal fentanyl in patients undergoing transurethral lithotripsy (TUL). In this randomized clinical trial, from April 2021 to September 2021, 54 patients with proximal urolithiasis candidates for TUL were enrolled. Patients were randomly categorized into two groups: group A received bupivacaine 10 mg and 0.5 ml of normal saline, while group B received bupivacaine 10 mg with 0.5 ml (25µg) of intrathecal fentanyl. According to our findings, about 74% of the patients were men, and the mean age of the patients was 66.14±22.46 years. The onset time of the sensory block, sensory block level, pain score, degree of relaxation, depth of the motor block, occurrence of anesthesia complications, oxygen saturation, and mean arterial blood pressure were not significantly different between the two groups. However, the duration of the motor block in group B was longer than in group A (p<0.001). Also, retropulsion was observed only in five patients (18.5%) in group A, significantly higher than in group B (p=0.019). Bupivacaine with fentanyl 25µg provided adequate spinal anesthesia with lower retropulsion in patients with urolithiasis who are candidates for TUL.