Objective:To investigate pharmacological effect of Cuscutae Semen by external use on experimental vitiligo in guinea pigs

and to provide the reference basis for the 〈Chinese Pharmacopeia〉（ChP）.Method: The vitiligo model was produced by chemical decoloration method.The Cuscutae Semen preparation was externally applied to the guinea pig skin（1.86

0.93

0.49 g · kg-1） for 40 days.Melanin distribution in skin and tyrosinase（TYR）

cholinesterase（CHE） and monoamine oxidase（MAO） in blood were determined.Result: The Cuscutae Semen showed good effects.Compared with the model group

it increased the skin melanin generation.Compared with the models

the Cuscutae Semen of 1.86 g · kg-1 groups had significant difference（P<0.01）

the Cuscutae Semen of 0.93 g · kg-1 group also showed difference（P<0.05）.For TYR

compared with the models（16.43±3.50） ng · mL-1

1.86 g · kg-1 and 0.93 g · kg-1 groups of Cuscutae Semen showed significantly difference（30.57±3.39） ng · mL-1 and（24.33±1.89） ng · mL-1 respectively（P<0.01）.Compared with the models

the Cuscutae Semen of 1.86 g · kg-1 group increased the activity of CHE [（94.20±6.73） U · mL-1]

（P<0.01） and reduced the activity of MAO [（36.42±3.99） U · mL-1（P<0.05）.Conclusion: The Cuscutae Semen by external use shows good effects on vitiligo in guinea pigs.