Environmental contamination due to the disposal of expired or obsolete drugs is a concern, since there is no specific Brazilian legislation, regarding disposal by the final consumer, thus reflecting the need for reverse logistics of medicines, after their consumption. The objective of this study was to survey the knowledge of pharmacists regarding their role in the reverse logistics of medicines and to understand the contribution of reverse logistics, aimed at the appropriate disposal of Group B waste, on a voluntary basis, by the population, in the municipality of São Paulo. A survey conducted through interviews with a hundred and sixty-one pharmacists demonstrated that 35% have partial knowledge of the postconsumer reverse logistics of their place of work and 16.8% have complete knowledge of the environmental harm resulting from the contamination of medicinal waste. The pharmacists also reported (10%) that there should be an educational plan for clients, and 50% of them agreed that incentives and disclosure, regarding the importance of reverse logistics for medicines, should be provided to consumers.