Sustainable development is one of the most debated issues today. Green marketing affects
the behavior of consumers, which are becoming more aware of environmental issues. In this
context, there are opportunities for innovation and business expansion, but firms must
observe ethical boundaries. This paper aims to discuss the role of advertising self-regulation
in fighting the claims to sustainability in Brazilian ads and labels. It sought to answer the
following research question: How to prevent greenwashing in commercial advertising?
Therefore, a narrative review of the literature about greenwashing was conducted. It was
also conducted a case study from eight decisions of the National Council of Advertising Self-
Regulation (CONAR) in proceedings initiated by consumer’s complaints, judged between
the years 2014 and 2016. The data-collection involved secondary data. This research uses
a qualitative approach. Regarding the nature of its goal, this is an exploratory research. It
was found that the most frequent complaint is the lack of evidence of the environmental benefits claimed by suppliers. Although it has no punitive power, CONAR, through its
recommendations, helps to inhibit the practice of greenwashing in Brazil
