This study compared reactive dyestuffs and vat dyestuffs in the dyeing of cotton. We investigated the possibility of reuse of the effluent generated, the ecological costs, and the colorfastness to water, rubbing, daylight, and perspiration. The experiments with vat dyestuffs showed slight advantage in terms of ecological costs, generating less molecules of carbon dioxide than the experiments conducted with reactive dyestuffs, lower consumption of energy, and greater possibility for reuse of treated effluent. In addition, vat dyestuffs exhibited decolorization efficiency above 99% and rates of total organic carbon removal over 90% in all cases, in addition to higher values in colorfastness properties.