Oleg Ptitsyn was a pioneer in protein folding studies: his discovery of molten globule folding intermediates revolutionized the field. He died in England on March 22, 1999, after a heart attack. Oleg Ptitsyn was born in St. Petersburg (Leningrad) on July 18, 1929, and took his M.Sc. in Molecular Physics at the University of Leningrad at the age of 22. He remained in Leningrad, at the Institute of High Molecular Compounds, first taking his Ph.D. in 1954 and then his D.Sc. in 1963 in physical and mathematical sciences. In 1967, he became Deputy Director of the Institute of Protein Research and simultaneously Head of the Laboratory of Protein Physics at Pushchino, at the Academy of Sciences Institute for Protein Research. He retained his position at Pushchino after becoming in 1992 a visiting member of the NIH Laboratory of Mathematical Biology, in the section of Robert Jernigan.