Objective To synthesize 11 C-methyldopamine (MDA) and to explore its feasibility as an agent for cardiac sympathetic nerve imaging.Methods 11 C-MDA was synthesized by direct N-methylation method and purified by semi-preparation reverse HPLC.Thirty Kunming mice were divided into five groups by random number table.The mice were respectively sacrificed at 2,5,10,20 and 30 min after injection of 7.4 MBq 11C-MDA.The lung,liver,spleen,kidney,stomach,intestine,brain,muscle,bone tissues and blood of mice were removed and weighed before radioactive γ-counting.The ％ID/g was calculated.Six Chinese mini-swine were divided into normal group (n=3) and inhibition group (n =3) for myocardial imaging.Mini-swine of inhibition group were injected with 10 mg/kg imipramine hydrochloride at 30 min before 11C-MDA (370 MBq) injection.The data were analyzed with SPSS 15.0 software.Results The synthesis of 11 C-MDA took 45 min with radiochemical yields of (20±3)％.The solution of11 C-MDA was colorless and the pH value was 6.5.The radiochemical purity was more than 98％ and the specific activity was 50 GBq/mmol.The myocardial uptake reached the peak value of (8.78± 1.18) ％ID/g at 2 min after injection of 11 C-MDA in mice.11C-MDA was mainly metabolized through liver and kidney.PET/CT imaging showed that 11 C-MDA was highly uptaken in swine myocardium and could be blocked by imipramine hydrochloride.Conclusions 11C-MDA can be synthesized by a simple and economic method.The high uptake rate of 11 C-MDA in the heart suggests it may be a potential agent for cardiac nerve imaging.