Periodic diameter measurements have been carried out on a number of the cold worked Zircaloy-2 pressure tubes in a steam generating heavy water reactor. Sufficient results are now available for statistical treatment, and they can be expressed as a function of the dose. The creep strain can be expressed equally well by two relationships, one involving a linear correlation with the dose and the other, a term of dose to the power of 0.6. After 30 years operation it is predicted that the pressure tube creep strains will be within the range of 1 to 3 percent. Observed differences in creep strain on tubes from different suppliers may be due to texture differences.