This book constitutes the proceedings of the Third International Workshop on Traffic Monitoring and Analysis TMA 2011 held in Vienna Austria on April 27 2011 - co-located with EW 2011 the 17th European Wireless Conference. The workshop is an initiative from the COST Action IC0703 Data Traffic Monitoring and Analysis: Theory Techniques Tools and Applications for the Future Networks . The 10 revised full papers and 6 poster papers presented together with 4 short papers were carefully reviewed and selected from 29 submissions. The papers are organized in topical sections on traffic analysis applications and privacy traffic classification and a poster session.