Objectives : The purpose of this study was to evaluate the bleaching effect of 3% hydrogen peroxide containing strip with primer in vivo. Methods : 22 female subjects aged from 20 to 39 years old were recruited after informed consent. They were divided into two groups with control and experimental group. Experimental group was bleached with 3% HP strip with primer, and control group received placebo for 14 days. Color changes were measured with Shade Eye-NCC (Shade Eye-NCC, SHOFU Co., Japan), Shade guide (VITA classical shade guide, $VIDENT^{TM}$, CA, USA) and digital camera image. All collected data were analyzed using SPSS 18.0. Results : At baseline, $L^*$ was $71.75{pm}3.2$ and $b^*$ was $14.90{pm}3.6$ in control, and $L^*$ was $71.3{pm}3.4$ and $b^*$ was $15.61{pm}3.7$ in experimental group. At day 14, $L^*$ was $71.35{pm}3.2$ and $b^*$ was $13.97{pm}4.3$ in control, and $L^*$ was $73.51{pm}2.0$, $b^*$ was $9.10{pm}3.0$ in experimental group. ${Delta}E^*$ of all teeth were statistically significant between the two groups. Final ${Delta}E^*$ was $7.15{pm}2.09$ at experimental group and $2.78{pm}2.93$ at control group, and the difference was significant (p<0.005). Color changes using shade guide also significantly decreased at 14th day compared with baseline at experimental group (p<0.005). Conclusions : 3% hydrogen peroxide strip with primer revealed effective enough to bleaching the human enamel during 14 days without any soft and hard tissue irritations.