The aim of this paper is to question the environmental reporting relevance, or in other wise its usefulness in the financial decisions taking. Considering that the investors trust depends on the demonstration of the disclosure reliability, this paper proposes the audit of the environmental reporting as a way to solve the problem of the reporting quality, which is regularly accused to be partial, convenient and focalised on good actions. As the financial audit, this new audit mission is then presented as an internal mechanism of governance supposed to constitute a guarantee of reliability and a determiner of credibility. In order to analyse the real taking into account of the audited or non-audited environmental disclosure in the financial choices, an association analysis has been conducted after having measured an environmental indicator regarding the content analysis of the sustainable reports published by a sample of 17 agrofirms in 2009. If this methodology has concluded to the profitability of the non-audited environmental reporting, the impact of the audit seems to be largely moderated or even negative. The analysis of this audit methodology and reports should provide explanation.