This volume contains the papers presented at the 8th International Symposium on Experimental Algorithms (SEA 2009).The symposium was held at the Te- nische Universit. at Dortmund, Germany, during June 4-6, 2009. The main theme of the SEA series is the role of experimentation and of algorithm engineering techniques in the design and evaluation of algorithms and data structures. Contributions are supported by experimental evaluation, methodological issues in the design and interpretation of experiments, the use of (meta-)heuristics, or application-driven case studies that deepen the und- standing of a problem's complexity. For each symposium, papers are solicited from all areas of algorithmic engineering research. Previous meetings, under the name of "Workshop on Experimental Al- rithms" (WEA), were held in Riga (Latvia, 2001), Ascona (Switzerland, 2003), Angra dos Reis (Brazil, 2004), Santorini (Greece, 2005), Menorca Island (Spain, 2006), Rome (Italy, 2007), and Provincetown (USA, 2008). The ProgramCommittee ofSEA 2009received64 submissions.Eachsubm- sion was reviewed by at least three ProgramCommittee members and evaluated on its quality,originality,and relevance to the symposium. Overall,the Program Committee wrote249 reviews with the help of almost 100 trusted external ref- ees. The Committee selected 23 papers, leading to an acceptance rate of 35.9%. The decision process was made electronically using the EasyChair conference management system. In additionto the accepted contributions,this volumealso containsabstracts ofthe invitedtalks givenby Heinz Bast(Intel), MichaelA. Bender (Stony Brook University and Tokutek, Inc.), and Marc Schoenauer (INRIA Saclay - Ile-de- France).