The objective of present study was to assess the safety and efficacy of nanocurcumin as an anti-inflammatory and antioxidant agent in adults with amyotrophic lateral sclerosis (ALS). We conducted a 12-month, double-blind, randomized, placebo-controlled trial at a neurological referral center in Iran. Eligible patients with a definite or probable ALS diagnosis were randomly assigned to receive either nanocurcumin (80 mg daily) or placebo in a 1:1 ratio. A computerized random number generator was used to prepare the randomization list. All patients and research investigators were blinded to treatment allocation. The primary outcome was survival, and event was defined to be death or mechanical ventilation dependency. Analysis was by intention-to-treat and included all patients who received at least one dose of study drug. A total of 54 patients were randomized to receive either nanocurcumin (n = 27) or placebo (n = 27). After 12 months, events occurred in 1 patient (3.7%) in the nanocurcumin group and in 6 patients (22.2%) in the placebo group. Kaplan-Meier analysis revealed a significant difference between the study groups regarding their survival curves (p = 0.036). No significant between-group differences were observed for any other outcome measures. No serious adverse events or treatment-related deaths were detected. No patients withdrew as a result of drug adverse events. The results suggest that nanocurcumin is safe and might improve the probability of survival as an add-on treatment in patients with ALS, especially in those with existing bulbar symptoms. Future studies with larger sample sizes and of longer duration are needed to confirm these findings.