ANASER is a system of 3 computer programs for the analysis of sera from multi-transfused patients, multiparous women and dialysed patients awaiting kidney transplantation, which react against one or more HLA antigens. This system permits: 1) the recognition of one or more HLA specificities in each serum using iterative analyses. 2) The calculations of correlation coefficients among several sera. 3) The drawing of positive serological reactions according to either a given sera or to a given antigen. It can be used for two main purposes: 1) to permit selection of the best sera for HLA typing (positive correlations). 2) To study the preimmunization of dialysed patients awaiting kidney graft. Owing to sequential comparison of the consecutive bleedings from the same individual, they allow the definition of a pattern of anti-HLA immunisation, and in the case of large spectrum antibodies, the specification of antigens not concerned by the antibodies produced (negative correlations). ANASER may help in the choice of the best compatible transplant for hyperimmunized patients, who need a precisely matched organ.