Research indicates that parents and other family members often grieve their child or relative's mental illness. This grief appears resultant from a profound sense of loss, which has been described as complicated and nonfinite (e.g., Atkinson in Am J Psychiatry 151(8):1137-1139, 1994; Davis and Schultz in Soc Sci Med 46(3):369-379, 1998; Jones in Br J Soc Work 34:961-979, 2004; MacGregor in Soc Work 39(2):160-166, 1994; Osborne and Coyle in Couns Psychol Q 15(4):307-323, 2002; Ozgul in Aust N Z J Fam Ther 25(4):183-187, 2004; Tuck et al. in Arch Psychiatric Nurs 11(3):118-125, 1997). This paper reviews existent research in this emerging field, with a focus on parents' grief experience in relation to their adult child's mental disorder. Studies that explore parents' and family members' grief, using both qualitative and quantitative methodologies, are considered. Research evidence for the association between parents' and family members' grief and other outcomes are discussed. Findings concerning the prediction of grief in parents and family members who have a child or relative with a mental disorder will be reviewed. Finally, this paper considers methodological and theoretical issues associated with existent research and presents options for further study.