The purpose of this study was to evaluate the effects of commercial home-tooth bleaching agents on the color of tooth. Twenty five sound extracted teeth were randomly divided into five groups. The color differences between before and after treatment with five types of tooth bleaching agents (7.5% hydrogen peroxide Nite White $Excel^{(R)}$, 10% carbamide peroxide Nite White $Excel^{(R)}$, 16% carbamide peroxide Nite White $Excel^{(R)}$, 10% carbamide peroxide Insta-BriteTM, 20% carbamide peroxide Insta-$Brite^{TM}$) were evaluated. The results were as follows: 1. By 2 week home tooth bleaching agent applications, the values ($L^*$) of bovine teeth increased as high as 4.38 $sim$ 8.80 when comparing to those of the samples before treatment, and the color difference (${Delta}E^*$) showed as high as 10.16 $sim$ 15.04. 2. 16% carbamide peroxide Nite White Excel induced significantly greater ${Delta}L^*$ than other test edgroups except for 7.5% hydrogen peroxide Day White Excel, and significantly greater ${Delta}E^*$ than other tested groups by 2 week bleaching agent treatments (p<0.01). 3. 16% carbamide peroxide Nite White Excel(${Delta}L^*$=8.80, ${Delta}E^*$=15.04) induced significantly greater ${Delta}L^*$ and ${Delta}E^*$ than 10% carbamide peroxide Nite White Excel(${Delta}L^*$=5.01, ${Delta}E^*$=10.16)(p<0.01), but significant difference between 10% carbamide peroxide Insta-Brite(${Delta}L^*$=4.38, ${Delta}E^*$=10.51) and 20% carbamide peroxide Insta-Brite(${Delta}L^*$=5.63, ${Delta}E^*$=11.23) was not shown in ${Delta}L^*$ and ${Delta}E^*$(p>0.01). 4. 16% carbamide peroxide Nite White Excel(${Delta}L^*$=8.80, ${Delta}E^*$=15.04) which were applied in night time induced significantly greater ${Delta}L^*$ and ${Delta}E^*$ than 7.5% hydrogen peroxide Day White Excel(${Delta}L^*$=8.47, ${Delta}E^*$=12.75) which were applied in day time. Conclusions: These results demonstrate that all the commercial home-tooth bleaching agents have appreciable bleaching effect on teeth, and the effects of home-tooth bleaching agents which are used during night time are affected by content of carbamide peroxide. Especially the whitening effect of home tooth bleaching agents that are used through night time is greater than that of short time-applying tooth bleaching agent.