This article describes the software and underlined decision support models for the immunophenotype diagnostics of leukosis (leukemia) and lymphomas adjusted for the marker or human leukocyte antigen (CD-antigen) coexpressions. Using the model knowledge base, the decision inference algorithm allows computing the degree of manifestation of the disease subtypes for the input immunophenotype features. Software provides the twostage diagnostics of the leukemia subtypes and the lymphoma diagnostics using the set of the developed rules, possibility to observe the diagnostic results and corresponding reference information. The patient data are organized according to the unified registration card, which provides the possibility to work at the different diagnostic levels: diagnostics of the extended groups of leukosis, diagnostics of the leukemia subtypes, diagnostics of the adult and child lymphomas.