This work compares the effect of amonopole antenna without cooling unit on a biological tissue and a monopoleantenna with cooling unit. Computer simulation was done using a computer softwarenamed COMSOL MultiphysicsTM, input power was varied from 10W to120W, with an interval of 10W, at different times, from 60s to 120s at aninterval of 60s. It was observed that the diameter ofthe lowest power (20W) decreased by -17.2% at 5mins, the length decreased by-32.9% and aspect ratio for the two antennas increased by 23.40%. For mediumpower (60W), at 5mins, the diameter decreased by -9.89%, length decreased by-37.9%, and aspect ratio decreased by 45.24%. The p-value obtained from diameterfor low power showed no significant difference for ablation without water cool(p > 0.005), but showed significant difference with water cool (p <0.005), diameter for medium power showed no significant difference, p >0.005 in both simulations, there was no statisticallysignificant difference in the diameter for high power (110W and 120W) for bothsimulations, p-value > 0.005. Theresult showed that inclusion of cooling unit reduced backward heating ofmicrowave antenna, ablation length, and ablation diameter of simulated tissue.