Background and Objectives: Regular physical activity is associated with improved quality of life and reductions of cancer-related mortality, but the underlying mechanisms are unclear. Moreover, Aloe vera may have anti-tumor and anti-inflammatory effects. In the current study, the effect of 6 weeks of swimming trainings along with Aloe vera supplementation, was investigated on serum levels of cyclooxygenase-2 and vascular endothelial growth factor in mice with breast cancer.   Methods: In this quasi-experimental study, 35Balb/c mice were acclimatized with laboratory conditions and swimming trainings, then mouse adenocarcinoma tumor balk was transplanted subcutaneously and after a week, they were divided into 7-animal groups, including exercise, exercise + extract, extract, and control (cancer). The fifth group )as the healthy control( included 7 mice. The exercise groups underwent swimming training for 6 weeks, and the extract groups also received 300mg/kg/day of aloe vera extract for 6 weeks. Blood samples were taken from the right ventricle 48 hours after the last session. The data were analyzed using one-way ANOVA at the significance level of p<0.05.   Results: The serum levels of COX-2 and VEGF significantly increased with tumor induction (p<0.05). After 6 weeks, VEGF levels in both exercise groups and COX-2 levels in the extract group, were lower compared to the cancer control group (p<0.05); However, these levels were higher than the healthy control group.   Conclusion: Based on the results, swimming and aloe vera supplementation may attenuate the increase of circulatory levels of COX-2 and VEGF caused by tumor induction but cannot normalize the elevated levels.