The role of the mechanical properties of the tissue in supporting lymph formation and/or progression in the diaphragmatic lymphatic network was studied in 7 rats. After anaesthesia overdose and mid-sternal thoracotomy, the diaphragm was excised and tissue strips were prepared. The average elastic module, E_t, of diaphragmatic tissue strips, assessed through tension tests using an electromagnetic machine equipped with a load cell of 22N, was 1.7 ± 0.3 MPa (1 SE). E_t was higher, although not significantly, when stress was applied in the longitudinal rather than in the transversal direction to diaphragmatic fibers axis and in strips excised from the ventral rather than the dorsal diaphragmatic region. The stress relaxation time constant after 10% strain was significantly higher (p <0.005) after elongation in the transversal than in the longitudinal fibers direction and in ventral than dorsal diaphragmatic tissue strips (p<0.01). The wall compliance calculated for a deep lymphatic vessel completely surrounded by isotropic diaphragmatic tissue was 0.068 nL/mmHg, i.e. two folds lower than in superficial submesothelial lymphatics. Modeling of stress distribution in the lymphatic wall suggests that compliant vessels may act as reservoirs accommodating large absorbed fluid volumes, while lymphatics with stiffer wall propel fluid taking advantage of the more efficient mechanical transmission of tissue stresses to the lymphatic lumen.