The paper reports the first demonstration of electromagnetically induced transparency (EMIT) in an optically thick medium. This phenomenon is achieved by applying a temporally smooth coupling laser between a bound state of an atom and the upper state of the transition to be made transparent. The transmittance of an autoionizing (ultraviolet) transition in strontium is significantly enhanced from exp(−20) without the coupling laser to exp(−1) with the coupling laser. The transparency results from destructive interference between two dressed states created by the coupling laser, which coherently phase-matches a fraction of the ground-state atoms to the upper state. The experiment uses a combination of a pumping laser and a coupling laser, both polarized and copropagating, to achieve the required conditions. The theoretical analysis confirms the experimental observations, showing that the destructive interference between the dressed states is crucial for the observed transparency. This work paves the way for the development of inversion-free lasers, Raman devices, and multiply resonant nonlinear optical devices.The paper reports the first demonstration of electromagnetically induced transparency (EMIT) in an optically thick medium. This phenomenon is achieved by applying a temporally smooth coupling laser between a bound state of an atom and the upper state of the transition to be made transparent. The transmittance of an autoionizing (ultraviolet) transition in strontium is significantly enhanced from exp(−20) without the coupling laser to exp(−1) with the coupling laser. The transparency results from destructive interference between two dressed states created by the coupling laser, which coherently phase-matches a fraction of the ground-state atoms to the upper state. The experiment uses a combination of a pumping laser and a coupling laser, both polarized and copropagating, to achieve the required conditions. The theoretical analysis confirms the experimental observations, showing that the destructive interference between the dressed states is crucial for the observed transparency. This work paves the way for the development of inversion-free lasers, Raman devices, and multiply resonant nonlinear optical devices.