AbstractThe copaiba tree (Copaifera spp.) produces an oleoresin which is highly valued due to its medicinal properties. The chemical composition of C. reticulata oleoresin was characterized, and its variability related to seasonal variation (dry and rainy seasons), to successive extractions, and to several factors associated with tree morphometry, disease, and surrounding vegetation structure was investigated. Oleoresin was collected from 24 C. reticulata individuals between October 2006 and March 2008. For seven individuals, oleoresin was extracted for a second time between three and nine months after the first extraction. For each tree, several morphometric variables, viz., the presence of termites, vines, and holes as well as the soil type and surrounding vegetation structure, were recorded. The chemical composition and concentration of the main volatile compounds were identified by GC/MS. Almost 100% of the constituents were sesquiterpenes, the three main ones being β‐caryophyllene, trans‐α‐bergamotene, and β‐bisabolene. A classification analysis separated the C. reticulata individuals in two main groups and further divided one of the main groups in two subgroups, which were defined by different concentrations of the three main compounds. The results showed high intra‐population variability in the composition and concentration of sesquiterpenes, this being comparable to the interspecific variability. It was not possible to determine a clear influence of environmental, morphometrical, and structural factors on the oleoresin composition, although some compounds varied according to the soil type, the volume of oleoresin extracted, and the crown surface.