Fentanyl or magnesium sulphate may improve the quality of peribulbar block. We compared the effects of adding either fentanyl or magnesium sulphate to peribulbar block in patients undergoing cataract surgery on the quality of globe akinesia.90 adult patients undergoing cataract surgery were randomly allocated into three groups. Peribulbar block was performed by a mixture of 4ml lidocaine 2%, 4ml bupivacaine 0.5%, hyaluronidase 150 IU diluted in normal saline to a total volume of 10ml in control group. 20μg fentanyl and 50mg magnesium sulphate (10%) were added to the same mixture in fentanyl and magnesium groups respectively. Onset and duration of lid and globe akinesia, adequate time to start surgery and duration of postoperative analgesia were recorded.Addition of fentanyl significantly enhanced the onset of lid (1.54±0.43min) and globe akinesia (2.19±0.75min) as well as adequate time to start surgery (6.23±1.8min) compared to both control (P<0.05) and magnesium sulphate (P<0.05) groups while the comparison between control and magnesium sulphate groups was statistically insignificant (P>0.05). Time of first analgesic request was significantly prolonged in both fentanyl and magnesium sulphate groups compared to the control group (P<0.05).Addition of fentanyl (2μg/ml) or magnesium sulphate (50mg) to peribulbar block in patients undergoing cataract surgery equally prolongs the duration of postoperative analgesia. In addition to this effect, fentanyl fastens the onset lid and globe akinesia and provides better akinesia score.