Phytochemical investigation of heartwood of Auxemma glazioviana (Boraginaceae) has led to the isolation of three benzoquinones, one hydroquinone identified as: oncocalyxone A (1), oncocalyxone C (2), glazioviana A (3), glaziovianol (4) besides allantoin (5) α-bisabolol (6) and α-cadinol (7). Their structures were determined based on spectral analysis, including 2D NMR experiments. Essential oil obtained from heartwood by hydrodistillation was analyzed by GC/MS. The major constituents were identified as α-bisabolol and α-cadinol. The oil was active against larvae of dengue (Aedes aegypti ) with DL50 2.98 ppm.