The objective of this study is to investigate the effect of bio-heat transfer from large blood vessels on freezing region size of tumorous liver tissue using cryo-freezing method. Bio-heat transfer, one of the cancer treatment method, in tumorous tissue has been investigated experimentally using cryo-freezing method for vessels. Investigated parameters are the blood mass flow rate, the diameter of vessel, the number of vessel, and the location of tumorous tissue. Study is carried out for nine different blood mass flow rates varying from 10 g/min to 1200 g/min. Tissues without blood vessel, with single, double and branched vessels are used for the experimental study. Vessels with inner diameter of 2.4, 3.2 and 4.0 mm are used. Liver of beef is employed as a tissue. Refrigerant is the nitrogen protoxide gas. Results show that the number of vessel, the diameter of vessel, the location of tumorous tissue, and the blood mass flow rate affect the freezing region size. Freezing region size decreases with increasing in diameter of vessel, number of vessel and blood mass flow rate. The large blood vessel located near the tumorous tissue affects the freezing time to destroy the tumor. The desired freezing region obtained in tumorous tissue with vessel develops later than the tumorous tissue without vessel. Results indicate that a tumorous tissue about 23 mm may be destroyed in a short time using cryo-freezing method when nitrogen protoxide gas is used as refrigerant gas.