In an MRI-room LED lighting system having a plurality of LED lighting fixtures and a power supply located outside of the MRI room, the improvement comprising: driver circuitry and PWM dimmer circuitry in each of the lighting fixtures and a dimmer control located outside of the MRI room for controlling the light output of the lighting fixtures, the dimmer control having a variable DC output to control the PWM dimmer circuitry in each lighting fixture, whereby conductor lines from the power supply and dimmer control do not require electrical shielding avoid interference between a MRI scanner and the lighting system.