Madre de Dios is one of the most diverse and best-conserved natural forests in Amazonia. However, this mega-diversity is threatened by illegal gold mining. The present study aimed to analyze the diversity, forest structure, and aboveground biomass in 3 sites reforested 20 years ago at Huepetuhe, southeast of Peruvian Amazon. Reforestation was carried out to recover abandoned mined areas using mainly exotic species. Three plots of 20 m × 20 m per site were used, where all individuals with diameter > 2.5 cm were inventoried. Twenty-five tree species were registered; only 3 were planted at the beginning of the reforestation (Tachigali sp. 1., Senna reticulata and Acacia mangium). The tree layer is dominated by spontaneous vegetation as Vismia baccifera, Cinchona micrantha, and Miconia poepigii and an exotic species (Tachigali sp. 1). We found M. poepigii trees with more than 20 cm of diameter and 18 m of height. Spontaneous species represent more than 80% of the species. The forest stored between 30 to 69% less biomass than secondary forests stands of similar age. Future projects should consider these native species for the ecological restoration of areas degraded by mining.