The 5th International Computer Science Symposium in Russia (CSR 2010) was held June 16-20, 2010 in Kazan, Russia, hosted by the Institute of Informatics of the Tatarstan Academy of Sciences and the Kazan State University. It was the?fth eventinthe seriesofregularinternationalmeetings,followingCSR2006 in St. Petersburg, CSR 2007 in Ekaterinburg, CSR 2008 in Moscow, and CSR 2009 in Novosibirsk. The opening lecture was given by Alexander Razborov, and seven more invited plenary lectures were given by Susanne Albers, Fedor Fomin, Juraj Hromkovi? c,RichardJozsa,PrabhakarRaghavan,Miklos Santha,and Uwe Scho- .. ning. This volume contains all the accepted papers and, at varying detail, the abstracts or extended abstracts of the invited talks. The scope of the proposed topics for the symposium was quite broad and covered basically all areas of the foundationsof(meaning:theoretical)computerscience.Unlikeinpreviousyears, no special application track was scheduled. We received 62 valid submissions in total, and out of these the Program Committee selected 30 for acceptance.