Users are the primary source of new techniques, i.e. systematic activities by which a complex task is accomplished. Even though user-generated techniques are a pervasive phenomenon which can be observed in many different contexts, existing research on user innovation has focused on product and service innovations. We focus on this important area of user innovation by studying four cases in the field of medical devices to analyse the processes by which users generate and diffuse new techniques as well as the interdependencies between user-generated techniques and subsequent changes to product use and product innovation. Our findings suggest that user innovation in techniques triggers product innovation by users and manufacturers. Therefore, users’ contributions to total innovation output are much higher than previously considered. Additionally, the diffusion of techniques differs significantly from the diffusion of new products. It can only be achieved with the involvement of diffusion agents and their interpersonal interaction and joint performance of the technique with possible adopters. As the diffusion of a technique is often a prerequisite for the diffusion of any related product, companies are forced to re-think their marketing strategies.