Background: Duration of spinal anesthesia depends on the type of anesthetic agent, dosage and additive materials such as epinephrine, ephedrine and opioid. We compared the duration of spinal anesthesia with lidocaine 5% with or without epinephrine in addict and non-addict patients undergoing inferior limb fracture surgery. Methods: This single blinded randomized clinical trial was performed on 201 males (height ranged 150-180 cm) who referred to the Shahid Bahonar Hospital of Kerman for the inferior limb fracture. Their physical class was matched to the American association standard class 1 and 2, and they were appropriate candidates for the spinal anesthesia. The addict or non-addict groups were each divided into two subgroups. 75 mg of 5% lidocaine was prescribed for one subgroup, and the other subgroup received 75 mg of 5% lidocaine plus 0.2 mg epinephrine. The level of primary anesthesia was elevated to T6. Duration of returning to the 4 primary sensory levels was measured since baseline. Findings: A significant increase in the duration of anesthesia level in both addict and non-addict patients receiving lidocaine plus epinephrine was observed compared to the subgroups receiving lidocaine alone (P < 0.01). Duration of decrease in sensory level in addict subgroups receiving lidocaine or lidocaine plus epinephrine was lower compared to non-addict patients (P < 0.0001). In addict subgroup receiving lidocaine alone, a significant decrease was observed in the time needed for decrease in sensory level (P < 0.01).Conclusion: According to the results of this study, regardless of the anesthetic agent being used, duration of spinal anesthesia was shorter in addict patients compared to non-addict ones. Addition of epinephrine to lidocaine 5% increased the duration of spinal anesthesia in both addict and non-addict patients.Keywords: Spinal anesthesia, Addict, Lidocaine, Epinephrine.