Recently in Tunisia, vegetables prices increased rapidly, especially green pepper, tomato and potato. The sharp rise in prices led to the deterioration of consumer’s purchasing power and the depletion of their food basket. Since price is the mechanism linking the different stages of the production chain, information on price transmission and causality can provide guidance on the actions to be taken by the actors. The results of the price transmission show a long-term relationship between retail prices and producer prices. The important role played by intermediaries influences the symmetric transmission mode. In the case of tomatoes, the transmission is asymmetric and the causality has gone from retail to producer prices, whereas for potatoes the transmission is symmetrical and the causality of production prices towards the retail price. For green pepper the transmission is also symmetrical and the causality is from retail price to the production price. The transmission depends on the causality but it also depends on the supply of the market and if the product is storable or not. Actions to be undertaken by the actors must concentrate on the control and transparency of commercial transactions along the food chain. Prices regulation must be placed on the wholesale level and not on the level of the producers in order to clear the margin of intermediaries and avoid the shortage of certain products in markets.