With about 50 species and subspecies, the diversity of primates in Peru is amongst the highest in the world. Primate field surveys, however, are still scarce for many areas. Peru's northern forests lie at the heart of the Tropical Andes and are home to four of the country's endemic primates: Aotus miconax, Callicebus oenanthe, Oreonax flavicauda, and Saguinus leucogenys. We present here an overview of results from more than five years of primate surveys in northern Peru. Surveys were carried out in the valleys and intervening highlands between the ríos Marañón and Huallaga in the departments of Amazonas, La Libertad, Huánuco and San Martín. Data were gathered between March 2007 and October 2012 from 36 locations at 26 sites. Surveys were carried out as part of biological inventories in proposed conservation areas. In all, 14 species were recorded from 11 genera. The presence or absence of a species was largely determined by altitude. The four endemic species were present in the majority of survey sites. The most common species encountered were Oreonax flavicauda, Ateles belzebuth, Cebus yuracus, and Aotus miconax. The highest species diversities were found at lower altitudes further from human development, although some species previously registered in these regions were not encountered. All areas visited suffered from at least some anthropogenic disturbance, with the majority showing high levels of habitat disturbance, deforestation and hunting.