BACKGROUND Hair coloring is broadly used by women and men either to change their natural hair color or to delay the onset of gray hair. Oxidative dyes may damage the hair, as chemical and physical processes are required to convert the fiber structure and, consequently, alterations in its mechanical and surface properties. OBJECTIVE The aim of this study was to evaluate the protective effect of silanetriol (and) Panthenol, PEG-12 dimethicone, and hydrolyzed silk (and) hydrolyzed milk protein (and) lactose as conditioner agents on hair treated with oxidative hair dye by protein loss, combability, and breaking strength. METHODS In this research, we analyzed the untreated hair (sample I) and the effect of oxidative hair dye emulsions, with or without conditioner agents (sample II) silanetriol (and) Panthenol (sample III), PEG-12 dimethicone (sample IV), and hydrolyzed silk (and) hydrolyzed milk protein (and) lactose (sample V) on Caucasian hair. The hair samples were submitted to protein loss quantification, breaking strength, and combing analysis. RESULTS For protein loss, the results were: IIa  = Va  > IVb  > IIIc  > Id . For the breaking strength: Ie  = IIe  = IIIe  = IVe  = Ve . For the combing analysis for wet and dry hair, the results were, respectively: IIa  > IIIb  = IVb  > Vc  > Id and IIA  > IIIb  = Vb  > IV c = Ic . Data classified by different letters presented statistically significant alterations, α = 5, P ≤ . 05, n = 15. CONCLUSIONS Based on these results, the incorporation of conditioner agents into emulsion blond color decreased the damage caused by the coloring process.