Estimates predict that in 2050 the world will have 9.7 billion inhabitants, which will cause an increase in the rates of greenhouse gases (GHG)s in the atmosphere due to human activities, mainly in urban centers. One of the leading gases is carbon dioxide (CO2), and Brazil is now the seventh-emission country. Considering this scenario, governments have created several proposals to reverse this situation, such as urban green spaces. Trees have several functions, such as fixing CO2 during photosynthesis and storing it as carbon in their biomass. Our aim in this study was to estimate the carbon stock and biomass of the aerial part of two tree species, Handroanthus serratifolius (Vahl) S. Grose (yellow ipê) and Mangifera indica L. (mango), at Avenida Mendonça Furtado, in the Municipality of Santarém, Pará State. The carbon storage can be estimated through allometric equations using the diameter measured at 1.37 m above ground (DBH) and the height of the trees. The findings show that the species M. indica L. stored more carbon with 2,273.92 kg and 102 individuals. The species H. serratifolius had 138 individuals and stored only 1,589.33 kg of carbon. Despite the smaller number of trees, the greater stocking of the M. indica species can be explained by the larger diameter of these trees when compared to the diameter of individuals of H. serratifolius. The stock of carbon stored in the form of biomass of the species used in urban afforestation can contribute to the reduction of greenhouse gases. This highlights the ecosystemic importance of urban green areas.