A number of previous investigations have reported that physical exercise renders immunopotentiating and antitumor therapeutic benefits to the tumor-bearing host. As these effects of physical exercise are mainly mediated through the modulation of hormonal and cytokine repertoire, it remains unclear if male and female tumor-bearing hosts show a gender-dependent differential response to the therapeutic action of physical exercise in tumor growth retardation. In the present investigation tumor growth retardation, following physical exercise was investigated in a gender-specific manner in a murine tumor model of a T-cell lymphoma designated as Dalton's lymphoma (DL). The results of the present investigation show that physical exercise of a tumor-bearing host on a treadmill results in a better retardation of tumor progression along with prolongation of survival time in male compared to female tumor-bearing host. Such gender dimorphism of the therapeutic benefits of physical exercise in tumor-bearing host was found to be associated with a gender-dependent variation in cell survival and induction of apoptosis in tumor cells. Moreover, expression of cell growth regulatory proteins-selectin, Hsp70, p53, CAD, SOCS, and IL-2 receptor-was found to vary in a gender-specific manner following physical exercise. The investigation also indicates the role of cytokines and macrophages in manifestation of gender dimorphism in the response of tumor-bearing mice to physical exercise. Thus, the observations of the present investigation suggest for the first time that the beneficial effects of physical exercise in a tumor-bearing host may be variable depending on the gender of the host.