C57BL/6 mice (3× n=9) were injected s.c. with vehicle (5% DMSO or saline), 1.5 or 5 mg/kg of the non-selective opioid antagonist naltrexone (NTX), 10 or 15 mg/kg of the DOR1/R2-selective antagonist naltrindole (NTI), 5, 6 or 10 mg/kg of the DOR2-selective antagonist naltriben (NTB). Thirty minutes after injection, ethanol and water consumption were measured over a 4 hour period. Ethanol preference = ethanol consumption/(ethanol consumption + water consumption). (*p<0.05; **p<0.01).