This paper pressnts a new boundary integral equation method for solving exteri-or boundary value problems of three-dimensional Heimheltz equation by using the multiple reciproc-ity method.Firstly

integral representations of the solution in an exterior domain as well as on itsboundary

which have the peculiarity that integral kernels are infin ite seriesea developed from thenormal fundamental solution of Laplace equation and independent of the wavenumber

are given andproved under the Dirichlet condition.Then

based on the representation of the solution on the bound-ary

boundary integral equations for solving the Dirichlet and the Neumann boundary value prob-lems are obtained

and remarks for some problems concerned with solving these integral equationsnumerically are made.Finally

the advantages of the proposed method

as compared with the conven-tional boundary element methods

are summarized.