PaCT-99 (Parallel Computing Technologies) was a four-day conference held in St. Petersburg on 6-10 September 1999. This represented the ?fth inter- tional conference in PaCT series, which take place in Russia every odd year. The ?rst, PaCT-91, was held in Novosibirsk (Academgorodok), 7-11 September, 1991. The second PaCT-93 was held in Obninsk (near Moscow), 30 August - 4 September, 1993. The third, PaCT-95, was organized in St.Petersburg, 12- 15 September, 1995 and the last fourth PaCT-97 was held in Yaroslavl 9-12 September, 1997. PaCT-99 was jointly organized by the Institute of Computational Mathem- ics and Mathematical Geophysics of the Russian Academy of Sciences (Novo- birsk) and by the Electrotechnical University of St.Petersburg. The purpose of the conference was to bring together scientists working with theory, archit- ture, software, hardware and solution of large-scale problems in order to provide integrated discussions on Parallel Computing Technologies. The Conference attracted more than 100 participants from around the world. Authors from over 23 countries submitted 103 papers and there were 2 invited papers. Of those submitted, 47 papers were selected for the conference; in ad- tion there were a number of posters presented. All the papers were internationally reviewed by at least three referees.