The cyclic deformation behavior of Pb-2 pct Sn solid solution alloy has been investigated. Results indicate that grain boundary migration and sliding occur in a systematic manner, giving rise to a series of migration markings on the surface of deformed specimens. Extensive cracking and cavitation takes place at migrating boundaries leaving an array of microcavities at high strain amplitudes. This feature was not observed at the low strain amplitudes investigated. Dynamic recrystallization and the evolution of a diamond grain configuration from an initial random distribution of grains were observed. These microstructural observations are discussed in relation to their influence on high temperature fatigue fracture. © 1988 The Metallurgical Society of AIME.