Infrared behaviour of on shell form factors in anN=4 supersymmetric Yang-Mills field theory

We discuss the infrared and mass singular behaviour of some on shell form factors which are calculated up to the two loop level in anN=4 supersymmetric Yang-Mills field theory. One of the outcomes of our investigation is that the finite terms in the perturbation series of the form factor are determined by exponentiating the lowest order term. The same phenomeno has been discovered in some infrared and mass finite quantities.