The evolution of histopathological lesions of sciatic and brachial nerves, bursa, thymus and spleen was studied during a long observation period following the challenge of chicken by the Marek's disease virus (MDV). Factorial analysis of correspondences allowed a synthetic study completed by classical statistical tests. In the nerves the sequence of type A, B and C lesions as demonstrated.At the same time a lymphoid depletion of bursa, thymus and spleen was observed This became less severe after a period and recovery in these organs was total. This study suggests the interest of multifactorial analysis for histopathological interpretation of lesions.