This article assesses the role of malaria and some social determinants on the agricultural development and more precisely on efficiency in the context of cotton crop in the Korhogo region in the North of Côte d'Ivoire. Data envelopment analyses (DEA) was first applied for the purpose of calculating relative efficiencies in production. A Tobit regression model was then used to explain the variation in the DEA scores and check the hypotheses that the efficiency deviations between farmers can be explained by the disparity of malaria morbidity rate among the farmers and their family, by social cohesiveness and cultural behaviour. Field data were collected by the authors between March 1997 and February 1998 on 700 rural households living in three rice production systems differently exposed to the malaria risk. Two malaria indicators were used for the active (11-55 years old) family members of the farm: Plasmodium falciparum infection rate and high parasite density infection rate. The DEA model was applied on the sub-sample of cotton growers (about one third of the households of the full sample). Results of the different DEA and Tobit models (depending of the production process hypothesis) show that high parasite density infection has a direct and indirect negative effect on efficiency in the cotton crop. They also show that more cotton growers in the village improve efficiency, although villages where cotton is growing more widespread have weaker social cohesion.