The degree of colour constancy can vary considerably between observers. Here we ask how the performance of colour constancy depends on the age of observers. We tested 60 subjects, aged between 15 and 75 years, all had normal or corrected to normal visual acuity and normal colour vision (Cambridge Colour Test). Colour constancy was measured for the achromatic appearance of a hexagonal testfield (2.4o x 2.4o, Ltest = 19.3 cd/m2, u’ = 0.197, v’ = 0.468 under standard condition), which was presented on a multicoloured background (18o x 18o, equal luminance and mean chromaticity as the testfield). Using a hue cancellation method, colour constancy was measured for simulated illumination changes along an equiluminant L-M or S-(L+M) axis. For 60 s adaptation time, the overall performance in colour constancy (80 – 90%) was independent of the age of the observers. For 5 s adaptation, colour constancy performance dropped with increasing age and most significantly for illumination changes along the S-(L+M) axis. The results cannot be explained by age related changes of the optical media of the eye or a generell loss in sensitivity. Instead the results indicate changes in the temporal dynamics of the neuronal process which contribute to colour constancy.