A quasi-state stress-field generated in an orthotropic elastic circular disk by a heat source rotating on a concentric circular path is investigated. An exact solution is developed in terms of doubly infinite series, using a stress-function approach. Numerical results are given for a boron-epoxy fiber-reinforced composite material and the effect of orthotropy on the distribution of thermal stresses is studied by comparing the orthotropic results with those for an isotropic material.