A boundary integral equation formulation for transient heat conduction problems with temperature-dependent material properties is proposed. Direct regular method, a technique used in elastostatic boundary element analysis, is applied for numerical solution. In order to verify the validity of the present formulation, two problems are solved. Present results show good agreement with the exact solution and the results obtained by finite difference methods and finite element method. To evaluate the coefficients of discretized boundary integral equations, some integral formulae are used instead of numerical quadrature. Application of these formulae can reduce the computation time to a large extent and achieve highly accurate evaluation.