A series of factorial experiments was performed in 1960-61 in State of São Paulo to compare the effects of three levels of spacing, three of NPK fertilizer and three of insecticide treatment in the production of peanuts (Arachis hypogaeaL). As an average of six experiments, the best yield increase was obtained with NPK fertilizers. Increasing plant population also induced satisfactory increase, whereas the average response to the insecticide treatment was small. A reduction in the stand of three experiments was observed and was associated to application of fertilizers in contact with the peanut seed.