We have compared three different fluorescent light sources (true light, blue light, true light + blue light) for phototherapy in 155 low birth weight newborn babies affected with non haemolytic hyperbilirubinaemia. Our data suggest that blue light is significantly more effective than true light. Surprisingly the association of true light with blue light is significantly more effective than both true light and blue light separately. The greater effectiveness associated with the better tolerance of true light + blue light respect to blue light only, makes it preferable than phototherapy regimen, even if more extensive study on its effectiveness and on short and long term side effects are need.