We have developed a new semiempirical three-dimensional (3-D) magnetosheath model to study the solar wind-magnetosphere interaction. Our goal has been to develop a model which takes into account the observed features of the interaction while keeping the model computationally simple. The model is semiempirical in the sense than the features obtained from global fluid models are used to guide the selection of the functional forms of the parameters in the magnetosheath. The model depends on a few free, empirically determined constants, and it includes separate magnetosheath and magnetosphere models. In the present study the basic features of the model are described, especially the morphology of the 3-D magnetic field in the magnetosheath. The applicability of the model is analyzed by studying the magnetic shear at the magnetopause and the interconnectivity of the magnetosheath and magnetospheric fields. Preliminary analysis indicates that already a simple phenomenological model can be a useful tool for analysis of solar wind-magnetosphere interaction. ¿ 2000 American Geophysical Union