Intellectual property rights, especially patents, are supposed to protect innovating firms by preventing their competitors from imitating them. The purpose of the system is to stimulate the pace of technological progress by encouraging firms to undertake research and development activities. This paper analyses the innovative behaviour of French firms to estimate the system's efficiency. The use of patents in no way seems automatic for firms and only certain types of innovation are patented. Only product innovations are thought to contribute significantly to the number of patents filed. Process innovations, on the other hand, would appear to follow a logic relatively independent of industrial property rights. Likewise, the patent system is reported to have a significant incentive effect on product innovations, but not on process innovations. The apparent incentives would therefore appear to be real, but biased towards product innovations. Moreover, the distribution of process innovation values obtained in our sample is concentrated and symmetric, whereas that for product innovations is much more spread out and asymmetric, as is the distribution of patent values.