The Canadian television show, Marketplace, stood by the claims and made a document with test information available.
Tests found an average of 53.6% chicken DNA for the oven-roasted version and 42.8% for the strips.
Testing of chicken from McDonalds, Wendy's, A&W, Subway and Tim Hortons was at a DNA lab at Trent University in Ontario.
Subway said it sent samples of Canadian products that Marketplace claimed contained 50% soy protein to Maxxam Analytics in Canada and Elisa Technologies in Florida.
The fast food chain said results show products were found to contain soy protein below 10 ppm, or less than 1%.
It added this is consistent with the levels added with the spices and marinade to help keep them moist and flavourful.
Suzanne Greco, Subway president and CEO, said the safety, quality and integrity of its food is the foundation of the business.
“That's why we took extra caution to test and retest the chicken. Our customers can have confidence in our food. The allegation that our chicken is only 50% chicken is 100% wrong.”
Subway’s US chicken suppliers are Perdue, West Liberty Foods, Keystone and Ed Miniat.
Dave Theno, Subway's chief of food safety and quality, said: "Our chicken is 100% white meat with seasonings, marinated, cooked and delivered to our restaurants. The chicken has no artificial colours, flavours or preservatives. Through years of testing, we've never seen results like the program claimed."