PURPOSE: The purpose of this study is to test the efficacy of various methods of fat harvesting in animal model by viability comparison with assay including cell counting, MTT assay, and histologic evaluation. MATERIALS AND METHODS: New Zealand white rabbits experiments were used. Groin fat pads were subjected to different harvest method varying ingredients of solution(Experiment 1: T1 solution= lidocaine 1000mg/L, epinephrine 1mg/L, sodium bicarbonate 10mgEq/L, Triamcinolone 10mgEq/L; T2 solution=lidocaine 1000mg/L, epinephrine 1mg/L, sodium bicarbonate 0mgEq/L, Triamcinolone 0mgEq/L) and pressure exerted on harvesting with Luer-Lock syringe connected to suction cannula.(Experiment 2: P1 group=3cc intermittent pressure; P2 group=10cc sustained pressure) Fat cell viability was assessed with cell counting with a hemocytometer, MTT assay, and histologic evaluation. RESULTS: Experiment 1 Cell count: T1=2.4/3.4/4.2, T2=9.6/8.4/7.2(x10(5) per mL); MTT assay: T1=0.516/0.41/0.453/0.412/0.421, T2=0.925/0.765/0.54/0.634/0.614 in 21 days(absorbance); Histology: T1 showed elongated and, different in size and shape, and ruptured adipocytes with only a few normal adipocytes whereas T2 showed central core of fat with almost intact fat cells Experiment 2 Cell count: P1=1.2/3.2/4.2, P2=1.2/2.4/3.8(x10(5) per mL); MTT assay: P1=0.256/0.245/0.258 /0.21/0.264, P2=0.12/0.231/0.245/0.313/0.281 in 21 days(absorbance); Histology: P1 showed somewhat evenly distributed normal-looking fat cells and P2 showed relatively irregular shape of fat cells with small blood vessel amongst adiopocytes. CONCLUSION: Viablity was higher in 'modified tumescent solution' without sodium bicarbonate and triamcinolone and we also found no significantly different viability between using intermittent pressure and using sustained pressure. But in terms of initial viability of fat cell, we can assume that lower intermittent pressure would make better clinical results.