Abstract: Pharmacological experiment of ~(99)Tc~m-MIBI and ~(99)Tc~m-CO-MIBI are performed by self-contrast in dogs.The data of pharmacokinetics parameters,biodistribution,T/NT are collected and calculated during and after photograph.Moreover,the whole body image,heart plane scintigraphy and tomography are investigated.Blood-pool clearance of ~(99)Tc~m-CO-MIBI conforms to two-compartment with 436.36±54.77 mL/h of blood clearance(CL) and T_(α(1/2))=1.46±0.13 min for the fast early clearance,T_(β(1/2))=97.30±20.50 min for the slow late clearance,which faster than that of ~(99)Tc~m-MIBI.The time-radioactivity curves show that the hepatic uptake curves are below the heart curves at about 40 min after ~(99)Tc~m-CO-MIBI injecting.The heart-lung and heart-liver ratios,which are measured at several time points,also demonstrate that ~(99)Tc~m-CO-MIBI have higher uptake and longer retain in myocardium,lower lung radioactivity and faster excrete from liver compare to ~(99)Tc~m-MIBI.During 10-120 min after ~(99)Tc~m-CO-MIBI injected,the excellent plane and SPECT can be obtained,perfect myocardial image without liver activity disturbance are gained after 40 min injecting.It suggests that ~(99)Tc~m-CO-MIBI have better pharmacokinetics properties and offer a great possibility as a new myocardial perfusion image agent.