In a randomized, double-blinded, controlled study, we evaluated the effect of diluting rocuronium 10 mg/mL to 1 or 0.5 mg/mL with 0.9% NaCl on the pain associated with IV administration of rocuronium with small doses given before succinylcholine or nondepolarizing agent administration. One hundred fifty patients undergoing surgical procedures that required general anesthesia were randomized into three groups. Group 1 received rocuronium 10 mg/mL. Groups 2 and 3 received I and 0.5 mg/mL of rocuronium, respectively. Patient demographics, pain scores, osmolality, and the pH of the solutions were recorded. Group 1 had the most intense and frequent pain response. Eighty percent of patients in this group reported pain on injection. In Group 2, the incidence and intensity of pain were significantly less when compared with those of Group 1. In this group, 38% of patients reported pain during injection. In Group 3, none of the patients experienced pain on injection. The pH values and osmolalities of study solutions were not significantly different among groups. In conclusion, in awake patients, dilution of rocuronium. 10 mg/mL at small doses given before succinylcholine or nondepolarizing agent administration of 0.06 mg/kg to 0.5 mg/mL with 0.9% NaCl is a simple and cost-effective strategy for preventing pain during IV rocuronium injection.