Two cases of lymphadenopathy grouped together by a common histologic diagnosis of angio-immunoblastic lymphadenopathy (A.I.L.) have been described. While in the first case there was a recent vaccination with BCG and tests positive for toxoplasmosis, the second case did not reveal any important anamnestic elements. The first case appeared to respond to antiprotozoan therapy while the second underwent lymphomatous degeneration with cerebral involvement. In view of the different clinical developments the existing nosologic position of A.I.L. comes under discussion. The great difficulty with which A.I.L. is demarcated from forms of reactive or neoplastic lymphadenopathy is emphasized by this example. Essential towards this is the study of lymphocyte markers and their in vitro function.