Irradiation growth, a shape change in the absence of an applied stress, is one of the factors limiting the performance of pressure tubes in CANDU-PHW reactors. Experimental data on irradiation growth in zirconium and its alloys that already exists in the literature is critically reviewed, as well as,_ the present models proposed for irradiation growth. New data is presented for growth in zirconium,zircaloy-2, Zr-2.5wt%Nb and the XL Alloy in which neon ion bombardment is used to simulate the reactor environment. The irradiation conditions and effects of microstructure are considered in full and recommendations are made with respect to future growth experiments.