In this work, the Ising model on a trilayer Bethe lattice is studied in terms of recursion relations for which the nearest-neighbor spins of each layer are coupled ferromagnetically and the adjacent spins of the nearest-neighbor layers are coupled either ferromagnetically or antiferromagnetically depending on the sign of the bilinear interactions for given values of the coordination number q. Besides the ground-state phase diagram, the phase diagrams of the model are also calculated for given values of the system parameters. It is found that the model presents both first- and second-order phase transitions for all values of q. In order to construct the phase diagrams, we have also studied the thermal and interlayer coupling constant changes of the layer magnetizations, the spin-spin correlation functions between the nearest-neighbor spins of the adjacent layers and the free energy of the model. (C) 2007 WIELEY-VCH Verlag GmbH & Co. KGaA, Weinheim.