A sympathy strike is a labour strike that is initiated by workers in one industry and supported by workers in a separate but related industry. Sympathy strikes are also called sympathy action, secondary strikes and secondary action.

The term sympathy strike implies that the purpose of the strike is to support, and express sympathy for, the primary strikers. In some cases, however, apparent sympathy strikes have been called for other reasons. For example, in Australia in the 1910s, sympathy strikes were sometimes called in order to extend a strike beyond the bounds of any one Australian state, thus making it eligible for handling by the Federal Arbitration Court .