Abstract: The invention relates to a fluorescent lamp, preferably a low pressure mercury discharge lamp for stimulating previtamin D3 production. The lamp has a discharge tube with a discharge gas filling. The inside wall of the discharge tube is covered with a phosphor coating for converting short wave UV radiation of the ionized discharge gas into longer wave UV radiation. The discharge tube is closed at both ends and provided with electrodes which are held and lead through a base cap at both ends. The base caps of the lamp are provided with contact pins for connecting the lamp to an electrical power supply. According to the improvement of the invention the UV light radiating coating of the discharge tube comprises a first phosphor for emitting light waves in the UVB spectrum and a second phosphor for emitting light waves in the visible light spectrum and for suppressing the emitted light in the UVB spectrum.