Was evaluated the toxic effect and rate percentage of loss of mass in grains of the essential oil of Piper aduncum on the black maize weevil Sitophilus zeamais through methods of contact with grains, applying the product directly onto the grains using concentrations of 0,25; 0,5; 1,0; 2,0 and 4,0 µl/g, and contact in filter paper, applying the product on filter paper and subsequent infestation with adults using concentrations of 0,08; 0,17; 0,35; 1,70 y 1,41 µl/ cm². By the method of contact over filter paper was obtained a CL 50 and CL 95 of 0,06 and 1,38 µl/cm², respectively. When the toxicity of the oil was evaluated at different concentrations was obtained a TL 50 and TL 95 of 63,36 and 140,67 h, respectively. By the method of contact with grains the CL 50 and CL 95 was 0,64 and 12,47 µl/g of product, respectively, and the TL 50 and TL 95 was in 5,79 and 204,49 h, respectively. The percentage of loss of mass in grains of corn caused by S. zeamais was determined, finding values ranging between 4,24 and 6,0%. According to the results obtained, P. aduncum presents toxic effect on S. zeamais.