This paper presents a literature review of empirical research related to the use and effect of online social annotation (SA) tools in higher education settings. SA technology is an emerging educational technology that has not yet been extensively used and examined in education. As such, the research focusing on this technology is still very limited. The literature review has aimed at presenting a comprehensive list of SA empirical studies not limited to a particular research method or study domain. Out of more than 90 articles that were initially found, only 16 studies met the inclusion criteria. Among the included studies were eight experimental or quasi-experimental studies and eight evaluation/survey studies. The SA empirical research has provided some evidence regarding the potential effectiveness of integrating social annotation tools into learning activities. Findings from the gathered literature were synthesized to provide recommendations for using SA technology in educational settings. (Contains 4 tables.)