We studied a large panel of monoclonal antibodies reactive on routinely processed paraffin-embedded tissue to determine their sensitivity and specificity in the diagnosis of 35 primary cutaneous large cell lymphomas of B- (n = 14) and T-cell origin (n = 21). The findings show that differentiation between clinically relevant subgroups can be obtained by a small panel of antibodies including L26, MB2, LN1, MT1, UCHL1, and Ber-H2. Pitfalls in the use of the reagents are discussed.