Adult T cell leukemia is a fatal malignant transformation caused by the human T-cell lymphoptropic virus type I (HTLV-I). HTLV-I is only associated with the development of this disease in a small percentage of infected individuals. Using two rabbit transformed T-cell lines; RH/K30 (asymptomatic) and RH/K34 (leukemogenic), we have investigated the expression of heat shock proteins (HSP) 90 and 70 and the role of anti-HSPs antibodies on virus production. HSPs surface expression was higher on RH/K34 than RH/K30 cells. Heat treatment of cells increased the expression of HSPs proteins and virus production; HSPs augmentation was stabilized after 12 h and virus production reached a maximum between 8 h–12 h then returned to normal level after 24 h of culture. Incubation of cells only with rabbit anti-HSP 70 antibodies prevented virus production specifically in the leukemogenic cell line. The results indicate a relationship between HSP 70 and virus production.