The effect of light of different coloured filters (blue, violet, green, yellow, pink and red) with various λmax (640, 635, 630, 457, 570 and 567 nm) was studied on the secretion of urokinase from mesangio proliferative glomerulo nephritis patient's kidney cells. The cells were grown on Dulbecco's medium. The maximum secretion of urokinase was observed in the presence of blue coloured filter (152.3 Plough units, control 80.42 Plough units) with an increase of 89.38% over control.