Word-of-mouth plays an important role as a communication channel during consumer decision processes, as a relevant and reliable source of information. Internet has allowed consumers to share online their opinions and evaluations with consumers all over the world. This study focused on word-of-mouth published on web stores, where consumers share their positive or negative opinions about products that are available at the store. Based on the Elaboration Likelihood Model, an experiment was carried out to evaluate effects of quantity and quality of negative online reviews on attitude and purchasing intention and the moderating effect of brand commitment. Results contribute to the knowledge about online consumer reviews and its influence on purchase behavior.