The aim of this paper is to evaluate the impact of collective marketing by FO on cocoa farmer’s price in Cameroun. This evaluation is done through the non-experimental method of impact evaluation which uses the techniques of “Propensity Score Matching”. Data used come from 2006 IITA cocoa baseline survey conducted between March 15 and April 15, 2006 and concern 601 cocoa farmers in Centre region in Cameroon during the 2005/2006 season. Results show that collective marketing has a positive and statistically significant effect on the net price received by farmers. This effect is estimated at 44 FCFA per kilogram of cocoa sold collectively, that means 8% increase on the individual sale price. The main recommendation is to promote the development of FO and collective marketing within FO. The development of FO requires a government policy to support the creation of FOs and by extension the effects of collective sales. Development of collective marketing can be done through creation of credit systems by FO to encourage farmers who sell to individual buyers under the constraint of credit received. This probably would increase significantly the share of supply captured by FO.