Background: Previous studies suggest that rhythmic compression of the abdomen (abdominal lymphatic pump techniques, LPT) enhances immunity and resistance to infectious disease, but direct evidence of this has not been documented. In this study, the thoracic duct of eight anesthetized mongrel dogs was catheterized, so the immediate effects of LPT on lymph flow and leukocyte output could be measured. Methods and Results: Lymph flow was measured by timed collection or ultrasonic flowmeter, and lymph was collected over ice under 1) resting (baseline) conditions, and 2) during application of LPT. The baseline leukocyte count was 4.8 ± 1.7 × 10 6 cells/ml of lymph, and LPT significantly increased leukocytes to 11.8 ± 3.6 × 10 6 cells/ml. Flow cytometry and differential cell staining revealed that numbers of macrophages, neutrophils, total lymphocytes, T cells and B cells were similarly increased during LPT. Furthermore, LPT significantly enhanced lymph flow from 1.13 ± 0.44 ml/min to 4.14 ± 1.29 ml/min. Leukocyte flux, computed from the product of lymph flow and cell count, was increased by LPT from 8.2 ± 4.1 × 10 6 to 60 ± 25 × 10 6 total cells/min. Similar trends were observed in macrophages, neutrophils, total lymphocytes, T cells and B cells during LPT. Conclusions: LPT significantly increased both thoracic duct lymph flow and leukocyte count, so lymph leukocyte flux was markedly enhanced. Increased mobilization of immune cells is likely and important mechanism responsible for the enhanced immunity and recovery from infection of patients treated with LPT.