In spite of undeniable recent progress, malaria today represents one of the global public health issues making the greatest impact on the economy. The present study carries out on the basis of the malaria indicator survey conducted in Cameroon in 2011. Only children under six years old are considered. We estimate the probability of being ill while benefiting from protection against malaria to be endogenous, which to our knowledge is new. Our findings allow an estimate of the effect of protection. Predictably, sleeping regularly under a bed net significantly decreases the probability of being ill. Our results also show that the children who are best protected are apparently those at greatest risk of infection. Households therefore seem to have a " good " perception of the risk of disease.