Abstract: An implantable patch antenna is designed to work in ISM band (2.4-2.5 GHz) for biomedical applications. The effect of human body on the different performance parameters of antenna is studied. To examine the effect of human body on antenna output characteristics, the patch antenna is tested by implanting in three layered body phantoms consisting of skin, fat and muscle and their performance is analysed by using different substrates for the same phantoms.