An approximate method based on the use of distributed Gaussian functions (DGF) to describe the interparticle distances is employed to study the rovibrational spectrum of trimers. Rotational energy levels are obtained by assuming that vibration and rotation are separated. Thus, eigenstates of the Hamiltonian for the zero total angular momentum, J = 0, are used as basis set to solve the rotational Hamiltonian. A procedure to identify the corresponding symmetry character for the rovibrational bound states is proposed. The DGF approach is applied to the case of the rotating Ar-3 trimer. The reliability of the method is tested by comparison with results from an exact hyperspherical coordinate calculation for J = 0, 1 and 6. (c) 2008 Elsevier B. V. All rights reserved.