Several techniques for semi-automatic or automatic detection of coagulation time in blood or in plasma analysis are available in the literature. However, these techniques are either complex and demand for specialized equipment, or allow the analysis of very few samples in parallel. In this paper a new system based on computer vision is presented. An easy image processing algorithm has been developed, which leads to an accurate estimation of the coagulation time of several samples in parallel. The estimation can be performed in real time using transputer architecture supported by a PC.