Abstract: A portable device is disclosed for monitoring the tanning of an individual in a controlled manner over a series of tanning sessions. The device time integrates the exposure to optical radiation and indicates when predetermined dosages of the radiation have been received for the purpose of obtaining a desired tan. The device which makes use of a personalized program in order to achieve a desired tan includes a series of filters, a light detector, an integrator, a programmable computer and an alarm. Light either from the sun or an artificial light source passed by the filter and impinging on the light detector is converted into electrical signals which are time integrated by the integrator and fed into the computer. In the computer the signals are processed with data signals corresponding to the precalculated radiation dosage limit for each one of a plurality of preselected tanning sessions and the calculated total radiation needed to achieve the desired tan.