In international food markets, voluntary traceability systems have increased their role in guaranteeing high safety and quality standards for the consumer. Such systems are also among the strategies firms employ to differentiate products and strengthen competitive advantage in both the national and international market. Voluntary traceability has significant implications on the organisation of economic relationships within food supply chains. This paper focuses on this aspect and analyses the effects of voluntary traceability on vertical co- ordination using a transaction cost perspective. The analysis makes reference to the Italian situation where the national standard organisation has introduced standard rules for voluntary traceability (UNI 10939; ISO 22005 at the international level). A survey was conducted by questionnaire to assess changes in transaction key factors (degree of asset specificity, uncertainty and frequency) and transaction costs after the introduction of voluntary traceability. The sample represent s all Italian firms certified UNI 10939, and consists of 190 firms. Respondents are 146. Factorial and Cluster Analyses were applied to highlight groups of firms with similar features. The empirical results reveal four different clusters in terms of a vertical reorganisation of transactions.