To the extent the chemical industry operates in a highly concentrated market with homogeneous products, co-operation between such companies can raise issues under competition law. Past industry practices have made the chemical industry a “traditional hunting ground” for competition authorities, as demonstrated by statistics. REACH provides a framework for co-operation between chemical companies. While such co-operation appears to be totally legitimate, it must be ensured that such co-operation does not become yet another reason for a close scrutiny of the chemical industry by competition authorities. Although REACH explicitly prohibits information exchange concerning market behaviour, co-operation is almost inevitable, particular in the supply chain, in order to successfully comply with REACH obligations. This article explores where the limits of lawful co-operation lie.