Pain is the most common presenting complaint in patients who present to the Emergency Department (ED). Renal colic pain is probably the worst excruciatingly painful event a person can endure. It has been suggested that desmopressin helps to relieve the pain of renal colic immediately. Because of low cost, ease of administration and low adverse effects of desmopressin comparison with opioids and NSAIDs, this study was conducted.The patients 18-55 years old with clinical diagnosis of renal colic were included. The presence of the nephrolithiasis had been approved in all patients in the past or confirmed in later follow up. In a double-blind, clinical trial in the ED of Imam Khomeini Hospital, Ahvaz, Iran, If patients had no exclusion criteria were randomly divided into two different treatment groups (n=120, 60 in each group). Group A received 40 μg of intranasal desmopressin, equal to 4 puffs of available products, combined with 75 mg intramuscular sodium diclofenac. Group B received 75 mg intramuscular sodium with 4 puff of intranasal placebo spray. A visual analog scale (VAS) score from 0-10, at baseline, 15, 30, 45 and 60 minutes of drug administration was utilized to assess the severity of pain. At 30 min, morphin sulfate 5 mg was injected if pain score ≥5. Ultimately at 60 min, morphine sulfate 5 mg intravenously injected again if any degree of pain.