We describe a newly developed method for fast determination of neutrophil chemotaxis and orientation in concentration gradients of chemotactic factors. The system implements video-based real-time scanning and image analysis of neutrophil migration under agarose, using an interactive easy-to-use computer program. Two methods for determining cell orientation are presented. No statistically significant difference between the methods was found. The analysis program distinguishes between chemokinetic and chemotactic behaviour of the cells (P less than 0.01).