We estimated the population density of Pectoral Antwrens (Herpsilochmus pectoralis) at the EMPARN (Rio Grande do Norte State Agriculture Research Company) Experimental Station, Brazil. During data collection, four transects ranging between 550 and 720 m were surveyed twice a week from February to August 2013. A total of 59.7 km were surveyed, where 77 sightings were made. We observed 1.3 individuals/km, and we estimated density to be 85 individuals/km². The density obtained for Pectoral Antwrens is compatible with that observed for the species in other studies and comparable to that found for other Thamnophilidae. The data generated in this study serve for future estimates of species conservation status.