This volume contains the proceedings of the Third International Conference on Algebraic Biology (AB 2008). Jointly organized by the National Institute of Advanced Industrial Science and Technology (AIST), Tokyo, and the Research Institute for Symbolic Computation (RISC), Hagenberg, Austria, it was held from July 31 to August 2, 2008 in the Castle of Hagenberg. Algebraic biology is an interdisciplinary forum for research on all aspects of applying symbolic computation in biology. The ?rst conference on algebraic biology (AB 2005) was held November 28-30, 2005 in Tokyo, the second during July 2-4, 2007 in Hagenberg. The AB conference series is intended as a bridge between life sciences and symbolic computation: On the one hand, new insights inbiologyarefoundbypowerfulsymbolicmethods;ontheotherhand,biological problems suggestnew algebraicstructures andalgorithms.While this pro?le has been established in the previous proceedings, the papers in the present volume demonstrate the continuous growth of algebraic biology. We received 27 submissions from 14 countries (Australia, Austria, Canada, China, Colombia, France, Germany, Italy, Japan, Norway, Russia, Switzerland, UK, USA), and 14 papers were accepted for publication. Each submission was assigned to at least three ProgramCommittee members, who carefully reviewed the papers, in many cases with the help of external referees. The reviews were discussedby the ProgramCommittee for oneweekvia the EasyChairconference management system.