Lifting, carrying, pushing and pulling at work are assumed to be related to increased risks of musculoskeletal injury, mainly in the low back and shoulder region. The implementation of products to reduce the physical load in heavy work is a well-known strategy to attack this problem. The success of these products depends not only on the product itself, but also on the process of product development and implementation. In this paper, seven cases are described where products have been developed to reduce the physical load on scaffolders, bricklayers, bricklayer's assistants, roofworkers, aircraft loaders, glaziers and assembly line workers. These products are described with special reference to the physical load problem in the occupational task, the process of product development, the nature of the product, the potential effects on physical load and the opinion of workers. From these cases, a list of key factors in product development contributing to the success of a product is composed. These concern among others a direct participation of workers, a wide analysis of risks, an analysis of potential negative side effects, and a systematic stepwise approach. Copyright © 2001 Elsevier Science Ltd.