Muscle fibre characteristics are involved in meat quality. The aim of this study is to propose a helpful method to evaluate the percentage of different fibre types using image analysis. Immuno-histological methods are practiced: cell outlines are identified by laminin antibody and cell type by their corresponding specific anti-myosin heavy chain. Different steps of image processing are developed. Fibre type percentages of two muscles studied (Longissimus thoracis and Semi tendinosus) in the “Blonde Aquitaine” breed are in agreement with results of literature. An accurate delineation of MyHC-based fibre types was obtained; automatic image analysis allowed a significant save in time. Hybrid fibres (containing simultaneously 2 types of MyHC) are easily characterized.