Background: Arthroscopic knee surgery is a surgical intervention that is frequently performed by orthopedic clinics and new studies are constantly carried out by anesthetists to ensure effective pain control. This study aimed to compare the efficacy of ultrasound-guided suprainguinal fascia iliaca compartment block (FICB) versus the combined adductor canal and obturator nerve block application in terms of postoperative analgesia in patients undergoing arthroscopic knee surgery under spinal anesthesia.Materials and Method: Sixty patients, who underwent arthroscopic knee surgery under elective conditions were included in the study. They were randomly divided into two groups, Group 1 (n=30) and Group 2 (n=30), using a lottery method. Patients operated under spinal anesthesia received ultrasound-guided suprainguinal fascia iliaca compartment block (FICB) for Group 1. The combined adductor canal and obturator nerve block for Group 2 at the end of the surgery. Intravenous patient-controlled analgesia (PCA) device containing tramadol was connected to all patients in both groups, and they were evaluated for Visual Analog Scale (VAS) scores at 0, 2, 4, 12, and 24 hours of ward follow-up. The amount of PCA used at 24 hours, additional analgesic use, development of side effects, mobilization capabilities, and satisfaction levels were assessed at the end of 24 hours.Results: There were no significant differences between the groups in terms of demographic characteristics and the type of surgery performed (p>0.05). In Group 1, where fascia iliaca block was applied the block administration time was observed to be significantly shorter compared to Group 2 (p<0.05). No significant differences were observed between the two groups in terms of postoperative VAS scores, PCA usage amounts, incidence of side effects, postoperative mobilization abilities, and satisfaction measures (p>0.05).Conclusions: Ultrasound-guided fascia iliaca compartment block alone can be effectively applied for postoperative analgesia in patients undergoing arthroscopic knee surgery, instead of combined adductor canal and obturator nerve block.