A widespread and commonly shared concern about food price inflation is now a worry that has seldom been felt in the world before, and is fuelling debates about the present and future situation of global food commodity prices. Increasing petroleum prices are suggested to be one of the factors that contributed to the rise in agricultural commodity prices. Vegetable oils are among the commodities that have experienced high prices growth. This study seeks to investigate the long-term relationship between the prices of petroleum and vegetable oils prices represented by palm, soybean, sunflower and rapeseed oils prices. To that end, the bivariate cointegration approach using Engle-Granger two-stage estimation procedure is applied. The study utilises monthly data over the period of January 1983 through March 2008. The results provide a strong evidence of long-run equilibrium relation between the two products prices. The estimates of the error correction models reveal a unidirectional long-run causality flowing from petroleum to each of the vegetable oils prices under study.