During the last decade medical applications of textile sensors have been growing rapidly and textile sensors are the focal research point for many sensor projects. Textile sensors are still not available as a mainstream product to replace conventional electric sensors and electrodes. Textile sensors can be integrated in a textile garment to measure vital signs of a human being. In this regard stretch sensors are able to measure breathing rate of a person. In this project we use seamless knitting technique to make stretch sensors using conductive fibers. The resistance difference between stretching and relaxing of these sensors gives a pattern for human breathing. Four knitting structures with different conductive fibers are made and tested with cyclic tester to construct a graph between resistance and time to find the knitting structure which gives the best results. Tests are also done to check the results after washing. These sensors can be used in breathing monitoring of patients during daily life.