Morphine, ethanol and cocaine were examined in place conditioning paradigm. After initial preferences were determined, animals were conditioned with morphine (5 mg/kg), ethanol (1 g/kg) and cocaine (5 mg/kg) alone or combinations of these drugs plus some calcium antagonists: nifedipine (5 and 10 mg/kg) and verapamil (5 and 10 mg/kg). Nifedipine prevented the ability of morphine and cocaine, but not of ethanol, to produce a place preference. Our results suggest that substances which can influence calcium distribution are involved in the rewarding actions of some drugs-morphine and cocaine. Dihydropyridine, a calcium channel antagonists might be clinically useful for the treatment of morphine and cocaine abuse.