This is the extended text of lecture notes by the author, which have been used at the Institute of Naval Architecture, University of Hamburg, and the Institute of Fluid Dynamics and Ship Theory, Hamburg University of Technology. The aerodynamics of ships and offshore structures are dominated by wind, that is by a random quantity depending on space and time. Probability adds to quantity. On the whole, ships are scarcely designed according to aerodynamic aspects and offshore structures even less. Form follows function. Actual forms are manifold. As the objects are mostly edged, the airflow is governed by separation. Theoretical tools are restricted; empirical assumptions and methods prevail. Tests on small-scale models of the objects or of structural components are convenient to predict full-scale performance. Full-scale measurements are scarce. Computational fluid dynamics (CFD) may be a practical alternative and, increasingly, a useful completion. Methods are rapidly improving. For practical applications see, for instance, Ferziger and Peri´c (1996). Methods and data available from the aerodynamics of land-bound structures can be useful. Reference is made to the monographs by Ito et al. (1990), Simiu and Scanlan (1986), Lawson (1980), and Sachs (1972). Hoerner (1965) and Hoerner and Borst (1975) offer extensive data of the pressures and forces on elementary bodies.