Following the biannual meetings in MUnster (1977) and Stanford (1979) the Third International Conference on Secondary Ion Mass Spectroscopy was held in Budapest from August 31 to September 5, 1981. The Conference was attended by about 250 participants. The success of the 1981 Conference in Budapest was especially due to the excellent preparation and organization by the Local Organizing Committee. We would also like to acknowledge the generous hospitality and cooperation of the Hungarian Academy of Sciences. Japan was chosen to be the location for the next conference in 1983. SIMS conferences...