The present paper analyses the electromagnetically-induced transparency (EIT) in a three-level ladder type system in an excitonic three-dimensional quantum dot (QD) with a parabolic potential in the presence of astatic magnetic field, a resonant probe field and a coupler field. Eigen values, wave functions, dipole matrix elementsand selection rules of the quantum system are calculated analytically within the effective mass approximation bysolving the corresponding Schrödinger equation and taking into consideration both the confinement and Coulomb potentials of the electron–hole pair. To illustrate the interaction with the optical fields, the analytical expressions forthe complex electric susceptibility, absorption, dispersion, group index (GI) and the combined effects of external factors such as magnetic field, hydrostatic pressure, temperature and dimensions of the QD are examined