Abstract Innovation is a crucial element for the company to maintain its competitiveness, but requires an enabling environment, specific resources and a particular organization to materialize. Despite the fact that innovation has attracted attention for many years among professional communities before academics, this phenomenon is experiencing some confusion in the literature causing ambiguities. We therefore tried harder to better understand innovation in Tunisian SMEs, by conducting an empirical study with a large sample. This empirical study shows that SMEs, despite having limited resources, use particular ways of doing things to stimulate product innovation. Among these ways of doing things, we will note the use of collaborations, contact with customers, the organization of management and the dissemination of information, the use of flexible equipment. Let's add to this the significant role that the entrepreneur plays. Moreover, contrary to what is found in the literature specific to large companies, the sums of money invested in R&D by SMEs are not significantly linked to their degree of innovation, while the formalization of these activities is. Keywords: Innovation, SMEs, research and development, new products, modified products.