$^{99m}Tc-MAG_3$ was synthesized, and biodistribution and blood clearance rate were compared with those of $^{131}I-OIH$ in mice and rats respectively. Finally renal image was obtained from a normal male volunteer before and after prescription of probenecid. The results obtained were as follows: 1) The uptake of $^{99m}Tc-MAG_3$ by kindey was higher than that of $^{131}I-OIH$ in mice 10 mins after injection (n=6, p<0.05), but slightly lower uptakes were found in all organs (kindney, blood, stomach, intestinge and liver) 2 hrs after injection. 2) For $^{99m}Tc-MAG_3$ $4frac{1}{2};alpha=2.4{pm}0.0;min,;tfrac{1}{2};eta=44.3{pm}7.4;min$, and blood clearance=$3.4{pm}0.5ml/min$, and for $^{131}I-OIH;tfrac{1}{2};alpha=1.8{pm}0.2;min,;eta=69.1{pm}9.5;min$, and blood clearance=$1.3{pm}0.1;min$ were found in rats. 3) From the renogram of normal male volunteer, we could find that tmax=130 sec and $tfrac{1}{2}=430;sec$ before probenecid prescription, and $tmax=150sim170$ sec and $tfrac{1}{2}=810sim1,170$ sec after probenecid prescriprion. From these results we concluded that $^{99m}Tc-MAG_3$ can be used instead of $^{131}I-OIH$ for obtaining renal image.