Marmosops juninensis is an endemic marsupial of the forests of Junín Department, central Peru. It is known by four specimens but has not been recorded in almost 50 years. We report two new specimens collected in 2011 that extend the range distribution of the species by 83 km eastward of the type locality. In addition, we describe some morphological characteristics of the species and provide description of its microhabitats: primary growth forest and cultivated fields of coffee and banana. Finally, we propose that M. juninensis qualifies for Endangered status according to IUCN criteria.