ABSTRACT Now, after many years the new ISO 12494: "Atmospheric Icing of Structures" has been finished and is ready for use. As it is the first standard, where all issues about ice and dimensioning for ice have been collected in the same standard, it differs in its substance from "normal" constructional standards (codes of practice) for actions on structures. Therefore, it may be necessary to introduce the use of it for meteorologists, designers and other interested engineers as well as other users. This paper explains how the structural designer or engineer should use the ISO 12494 and point out the most important facilities for this use. The types of actions specified are ice mass as well as wind action from wind load on the iced structure. The standard has been prepared in such a way that it invites to use small "calculation tools" which very much facilitates the use of information and improves the understanding of the whole structure of the standard. The standard could be used also even if a National Standard of icing already exists, because more or less of the content could be adopted by the National Standard without any problems or contradictions. The ISO 12494 could e.g., be used for preparing icing maps for countries or part of countries, as National Bodies often want this. Introduction As it is the first time a standard include all necessary information for dimensioning structures for both glaze and rime, a guidance for its use may be appropriate, and this paper might be a start. The definitions of Ice Classes for both glaze and rime as well as the principle for using the standard including examples of the most needed tools is presented and commented.