This study was carried out to investigate the effect of rosemary essentialoil on hair growth in a shaving animal model of C57BL/6 mice. Five weeks old male mice were divided into four groups including normal group (N; saline), vehicle control group (VC; jojoba oil), positive control group (PC; 3% minoxidil) and experimental group (E; 3% rosemary oil) and they were topically applied with an amount of 100?L once a day, 6 days a week, for 4 weeks. At 4-week application, hair regrowth on dorsal skin in E (42%) and PC (55%) groups was much faster than N (3%) and VC (20%) groups in gross observation. Hair follicle number, follicle depth and dermal thickness of E and PC groups were significantly higher (p<0.05) than N group in histological observation. And number of mast cells in dermis and hypodermis of E and PC groups were significantly lower (p<0.05) than N and VC groups. These results indicate that rosemary oil effectively stimulated hair growth in an animal model.