This volume contains a selection of papers presented at the 10th Workshop on Membrane Computing, WMC 2009, which took place in Curtea de Arge, s, Romania, during August 24-27, 2009. The?rstthreeWorkshopsonMembraneComputingwereorganizedinCurtea de Arge, s, Romania - they took place in August 2000 (with the proceedings p- lished in Lecture Notes in Computer Science, volume 2235), in August 2001 (with a selection of papers published as a special issue ofFundamenta Inform- icae, volume 49, numbers 1-3, 2002), and in August 2002 (with the proceedings publishedinLectureNotesinComputerScience,volume2597).Thenextsixwo- shopswereorganizedinTarragona,Spain(inJuly2003),inMilan,Italy(inJune 2004), in Vienna, Austria (in July 2005), in Leiden, The Netherlands (in July 2006), in Thessaloniki, Greece (in June 2007), and in Edinburgh, UK (in July 2008), with the proceedings published as volumes 2933, 3365, 3850, 4361, 4860, and5391,respectively,ofSpringer'sLectureNotesinComputerScience. The workshop changed its name in 2010, and the series will continue as the Conference on Membrane Computing, with the next edition, CMC11, to be held in Jena, Germany. The tenth edition of WMC took place in Hotel Posada in Curtea de Arge, s (http://www.posada.ro/)anditwasorganizedbytheNationalCollege"Vlaicu Voda" ? of Curtea de Arge, s, the University of Pite, sti, Romania, and the Institute of Mathematics of the Romanian Academy, Bucharest, under the auspices of the European Molecular Computing Consortium (EMCC) and IEEE Compu- tional Intelligence Society EmergentTechnologies Technical Committee Mole- lar Computing Task Force, with the ?nancial and organizational support of the Council of Arge, s County and Seville University.