Directly-measured tree biomass data from Madre de Dios, Peru. Fifty-one trees were weighed, with diameters ranging from 10 to 169 cm. Twelve trees have diameters exceeding 100 cm. Dataset includes diameter, total height, height of the first branch, wood density, crown radius, crown area, an architectural classification (monopodial or not), wood density, stem mass, crown mass, and total aboveground biomass.