Hyperbaric prilocaine 2%-fentanyl versus hyperbaric bupivacaine 0.5%-fentanyl for Intrathecal injection in perianal surgeries Yasser M. Nasr Associate Professor of Anesthesia, Intensive care, and pain management , Faculty of Medicine, Zagazig Universit, Egypt : prilocaine is an intermediate acting local anesthetic that can be used B for spinal anesthesia in short duration surgeries. This might help reducing the stay in both postanesthesia care units (PACU) and hospital stay. Aim of the study: is to compare regression time of spinal anesthesia induced by hyperbaric prilocaine 2% with 20µ fentanyl versus hyperbaric bupivacaine 0.5% with 20µ fentanyl in perianal surgeries. Methods: Eighty patients were allocated into 2 groups: Control group (Group C: n=40) were given 1.5 ml (7.5 mg) hyperbaric bupivacaine 0.5%+ 20µ fentanyl while Group P (n=40 patients) were given 1.5 ml (30mg) hyperbaric prilocaine 2%+20µ fentanyl. In both groups, regression of spinal anesthesia (sensory and motor), time to spontaneous micturition, postoperative analgesic behavior, duration of PACU and hospital stay were evaluated. Results: Maximum levels of block in both groups were comparable. Sensory and motor block regression times were statistically shorter in Group P. Time to spontaneous voiding and time to unaided walking were shorter in Group P. There were no significant differences in duration of PACU stay between the two groups. Time till home readiness was significantly shorter in Group P. There were no cases of postoperative urinary retention or transient neurologic symptoms Conclusion: Both 30 mg hyperbaric prilocaine 2% plus 20 µg fentanyl versus 7.5 mg hyperbaric bupivacaine 0.5% plus fentanyl 20 µg are equipotent and safe when used intrathecal in perianal surgeries. However, prilocaine is superior to bupivacaine regarding block regression, and home readiness. Keywords: Intrathecal, prilocaine, bupivacaine.