Cell migration is an important biological phenomenon which depends on a number of internal and external factors. One of such factors can be the mechanical properties of the environment which can have an impact on the cell's regulatory pathways through so-called mechanotransduction. Ultimately, these properties can also influence the process of cell migration. The goal of this work is to investigate how substrate stiffness (elasticity) changes basic migration parameters of migrating cells. Fish keratocytes migrating on polyacrylamide hydrogels have been used as a model of fast migrating cells. Cell migration have been tracked with optical microscopy, employing a time-lapse technique. Migration parameters have been determined from image analysis. This study has shown a systematic decrease of some of the key migration parameters-average cell speed and angular persistence-with a simultaneous increase of substrate elasticity. The results demonstrate that the elasticity of the substrate is the key factor in cell migration. It determines speed and angular persistence, which proves that mechanical parameters of the environment can affect cellular processes. A detailed knowledge of mechanotransduction processes can have major implications for tissue engineering and for the understanding of metastasis.