The influence of the grade of titanium dioxide pigment on the yellowing of aged paint films has been studied. Using several yellowing environments, the results showed that an anatase pigmented film was more prone to yellowing than a non-coated rutile pigmented film, which in turn yellowed slightly more than a coated rutile pigmented film. The various surface treatments to which most rutile titanium dioxide pigments are subjected did not affect the rate of yellowing, although a chloride process pigment and a fine crystal grade exhibited slightly less yellowing than a sulphate process pigment. From the point of view of retarding yellowing, the use of zinc oxide and acetoacetates was studied; it was evident that the former was more effective, particularly in the colloidal form.