This review represents a comprehensive coverage of results reported in the literature over last 50 years on the methods of studying hot tearing and mechanical properties of semi-solid aluminium alloys; the mechanical properties of these alloys in the semi-solid state; and hot tearing criteria. While compiling this review, the authors attempted to include in it all available sources including quite a few works never published in English before. The review consists of three parts. The first part introduces the reader to the phenomenon of hot tearing. The second part describes different techniques for testing metallic alloys in the semi-solid state and summarizes reported results on strength and ductility of semi-solid model and commercial aluminium alloys. The third part describes the methods for assessing hot tearing susceptibility of aluminium alloys, gives the results on hot cracking of various aluminium alloys and discusses different hot tearing criteria. (C) 2003 Elsevier Ltd. All rights reserved.