Air-dried imprint preparations are conveniently produced from human lymphoid samples without the special methods required for snap-freezing tissues or rendering them into suspensions. T-cells, T-cell subsets (helper and suppressor), and HLA-DR-positive cells (B-lymphocytes, monocytic-histiocytic cells) can be identified in such imprints by the use of commercially obtained mouse hybridoma antibodies with a simple two-step immunoperoxidase method. Direct nuclear morphologic correlation with surface determinants is achieved by this method. Immunoreactivity is retained only eight to 10 days in such air-dried preparations, and attempts to prolong reactivity have been unsuccessful so far.