Summary: This paper reviews the background to and the current status of analyses developed to address the problem of icing on aircraft. Methods for water droplet trajectory calculation, ice accretion prediction, aerodynamic performance degradation and an overview of ice protection system modelling are presented. The paper also addresses the issues involved in the development of icing analyses, including problem formulation and assumptions, solution techniques, validation and incorporation of empirical inputs where a purely theoretical approach is not feasible. Results are presented to illustrate the capabilities of the analyses when applied to practical design problems. Recommendations are made for further research.