This book constitutes the refereed proceedings of the 7th International Conference on Computational Methods in Systems Biology, CMSB 2009, held in Bologna, Italy, August 31 - September 1, 2009. The 18 revised full papers presented together with the summaries of 3 invited papers were carefully reviewed and selected from more than 45 submissions. The papers cover theoretical or applied contributions that are motivated by a biological question focusing on modeling approaches, including process algebra, simulation approaches, analysis methods, in particular model checking and flux analysis, and case studies.