This study aimed to prepare a novel radiopharmaceutical for the detection of brain disorders at early stages in susceptible patients.Promazine hydrochloride was labeled with ¹²⁵I by direct electrophilic substitution reaction with high labeling yields of 92.6 ± 3.24 %. The labeling yield and in vitro stability of ¹²⁵I-promazine were determined by paper electrophoresis, paper chromatography (PC) and High performance liquid chromatography (HPLC). In vitro studies showed that the highest radiochemical yield of ¹²⁵I-promazine (92.6±3.24%) was stable up to 6 h. Biodistribution studies showed that maximum uptakes of ¹²⁵I-promazine in the brain of mice was 5.4 ± 0.18 % injected dose/g after 30 min post-injectionwhich is higher than that of ^99mTc-HMPAO and ^99mTc-ECD (2.25 and 4.7 %, respectively), so this confirms the high specificity and selectivity of this radiotracer for brain and could be used for brain imaging instead of the commercially available ^99mTc-HMPAOand ^99mTc-ECD.