[en] The single-electron non-relativistic electric-dipole oscillator strength, f, is used in the hydrogenic model for the calculation of the radiative properties of hot plasmas. In this paper the effect of relativity on the electric-dipole oscillator strengths in a single-electron atom is calculated for δl = +1, δn = +1 transitions between discrete levels of principal quantum number 1-5 and Z between 1 and 90. The effect of relativity is always to decrease f. The effect of retardation is shown to be small except for 1s-2p transitions. (author)