The research presented in the thesis and the two papers intends to improve LCA methodology and practice so that use and emissions of textile chemicals can be included in LCA studies of textile products, and the results thereof can provide useful guidance to decision makers in the textile industry. Three research questions are answered: 1) if the toxicity impact potential of textile chemicals is covered in LCA studies of textile products, 2) if the environmental performance ranking of textile products will be affected by including the toxicity impact potential of textile chemicals in LCA studies and 3) what the main challenges are in using LCA to assess the toxicity impact potential of textile chemicals. The research method has been designed to explore the challenges and suggest improvements to LCA methodology based on literature studies, case studies and triangulation with other applicable methods for calculation of toxicity impact potential.