Since its discovery by Kohler and Milstein in 1975, hybridoma technology has found a wide use in almost every field of biology and medicine. A general and simple approach for developing monoclonal antibodies is to use splenocytes from immunized mice. In the present study, 10 fusion experiments were carried out to analyze the hybridization efficiencies of mouse myeloma cells with lymphocytes derived from spleen, lymph node, and bone marrow and we found a higher yield of antigen specific antibody producing hybridoma lines when the lymph nodes were used.