A study of the social impact of Sudden Infant Death Syndrome (SIDS) in 40 families in Ireland (40 mothers: 29 fathers and 78 siblings) revealed a profound influence on family function. Less than half the parents felt an acceptance of the loss at a mean interim of 2.9 years post SIDS. Family dysfunction was manifested by marital problems and prolonged grief reactions. Interpersonal support through family, friends, relatives or neighbours appropriately assisted a third of families. Medical information when provided to parents contributed to a more normal grief process, but lack of postmortem information contributed to pathological or unresolved guilt in a third of parents and anger in nearly half the sample. Health professional and voluntary aftercare at community level was inconsistent in meeting parents' need for information, advice and support. A primary, preventive health care approach, based on a co-ordinated policy of aftercare to SIDS families, at hospital and community level is recommended to facilitate parents' resolution of grief, and counteract the onset of adverse psychosocial effects.