Antimicrobial activity and essential oils yield of Pimenta pseudocaryophyllus var. pseudocaryophyllus (Gomes) Landrum, Myrtaceae. The essential oils of Pimenta pseudocaryophyllus var. pseudocaryophyllus specimens from two distinct locations: Campos do Jordão and Itaquaquecetuba, were tested to detect antimicrobial activity to the microorganisms Aspergillus niger, Penicillium verrucosum, Escherichia coli and Staphylococcus aureus in medium culture. The method utilized was impregnated filter paper in essential oils . The essential oil extraction was made through method of Clevenger modified for Wasicky in 1963, for the hydrodistilation. The monoterpene citral was tested under the same conditions of the essential oils. The microorganisms development under these conditions presented the following results: the oil of P. pseudocaryophyllus var. pseudocaryophyllus from Campos do Jordão had the same antimicrobial activity that citral, inhibiting in 72,7 % and 71,5%, the growth of the microorganisms, significantly higher than the level of the oil originated from Itaquaquecetuba that presented 38,8% of inhibition. About to the microorganisms, the growth inhibition was higher for P. verrucosum (83,3%), followed by A. niger (71,9%) and S. aureus (70,3%). The minimal inhibitory activity was presented by E. coli (18,4%). Except for E. coli, which presented the same characteristic of inhibition for two oils and the citral, all the other factors presented significant interaction, showing specificity of reaction for each one of the levels of these factors. These data demonstrated the antimicrobial potential of the essential oil of the Pimenta pseudocaryophyllus var. pseudocaryophyllus The yield of essential oil collected in Campos do Jordão was 2,3% and the species collected in Itaquaquecetuba was 1,9% (w/v).