Maricopa County officials finished counting ballots Saturday on Proposition 203 and said of 1.67 million ballots counted, proponents of medical marijuana use won by 4,341 votes, or 50.13 percent, The Arizona Republic, Phoenix, reported Sunday.
Fourteen other states already permit the use of medical marijuana.
Under Arizona's proposition, medical doctors could sign documents recommending patients with illnesses such as cancer, glaucoma, HIV/AIDS, Hepatitis C and Alzheimer's disease be allowed to obtain marijuana from regulated outlets.
The Arizona Department of Health Services is expected to begin reviewing who will dispense the marijuana and patient applications by next April, the newspaper said.
Medical marijuana use has not been formally approved by the U.S. Food and Drug Administration.