The aim of this study was to investigate the effect of two different bleaching procedures, home and in-office bleaching using Whitesmile products on enamel ultrastructure, the microhardness of human treated enamel and the color of teeth. Twenty extracted sound and healthy human premolars were collected. Since they may differ in many properties as the enamel thickness, there was standardization through the use of the same tooth to be investigated before and after bleaching. In each tooth, the crown was sectioned longitudinally in two directions, mesio-distally and bucco-lingually resulting in four quarters representing four groups. Each study group consisted of 20 specimens. Group I (16% carbamide peroxide) used for nine days, five hours per day, Group II (22% carbamide peroxide) used for nine days, five hours per day. Group III (32% hydrogen peroxide) used in three applications, fifteen minutes each (light activated) and Group IV(38% hydrogen peroxide) used in three applications, fifteen minutes each (light activated). ESEM results revealed increase in enamel porosity, increase in surface roughness and loss of aprismatic layer in Groups I and II specimens (16% carbamide peroxide and 22% carbamide peroxide respectively). While Groups III and IV (32% hydrogen peroxide and 38% hydrogen peroxide respectively) results showed increased enamel porosity, areas of erosion and increase in depth of enamel grooves. Statistical analysis of microhardness revealed significant decrease in Groups II, III and IV (22% carbamide peroxide, 32% hydrogen peroxide and 38% hydrogen peroxide respectively) while that of Group I (16% carbamide peroxide) showed no statistical significance. Statistical analysis of color using the spectrophotometer showed significant changes in ΔE (difference in color) in all groups. Where group IV (38% hydrogen peroxide) showed the highest values and group I (16% carbamide peroxide) showed the least values.