The stress intensity factor corresponding to a radial crack emanating from the internal boundary of a tube is calculated by the boundary collocation method. Uniform external tension on the outer boundary is chosen as the applied load. By using superposition it can be shown that this solution is identical with that of a uniform internal pressure acting in the tube and on the crack surfaces. The present results calculated by this method coincide very well with the existing solution in most cases. For small wall ratios, this method gives better results.