Previous studies have shown that antibody-forming cells (AFC) produced in the lung-associated lymph nodes after lung immunization enter the blood and are subsequently extravasated into immunized lung lobes. This study evaluated AFC in blood and lung lavage fluids following simultaneous stimulation of the thoracic and popliteal lymph nodes with two antigenically distinct immunogens. Five dogs were immunized in the hind feet with rabbit red blood cells (RRBC) and in the left cardiac lung lobe with sheep red blood cells (SRBC). The number of anti-SRBC and anti-RRBC AFC in the blood and lavage fluids was periodically evaluated. The results indicated that both immunizations significantly increased the number of AFC in the blood. The number of AFC to RRBC and SRBC antigens was significantly higher in the immunized lung lobes than in the control lung lobes. A comparison of the number of RRBC and SRBC AFC in the immunized or control lung lobes, relative to the number of RRBC and SRBC AFC in the blood, indicated that AFC to both antigens entered the lung at the same rate. We conclude that AFC produced in distant lymphoid tissues enter the lung from the blood as readily as AFC produced after lung immunization.