Abstract: The inhibitory effects of ethanol or water extract from garlic on Phytophthora parasitica were determined by a bacteriostatic method on agar plates. The results indicated that:garlic extracts, particularly the ethanol extract could obviously inhibit Phytophthora parasitica, the inhibitory effects improved with the ncrease of extract's concentrations. The inhibition rates of ethanol extracts at the concentrations of 0.20 and 0.30 g/mL were 100.00%; that of water extract at the concentration of 0.30 g/mL was 100.00%. The EC50 of water and ethanol extracts were 0.04 and 0.03 g/mL, respectively. It suggested that garlic might be a potential raw material in developing Phytophthora parasitica inhibitor.