Purpose: To examine the association between communication with parents and self-harm in 14-19-year-old adolescents. Methods: A total of 36 female and 16 male adolescents presenting to the accident and emergency department of a general hospital; 52 hospital-based controls were interviewed and studied using the following scales: Parent-Adolescent Communication Scale, Family Adaptability and Cohesion Evaluation Scale, Adolescent-Family Inventory of Life Events and Changes Scale, Children's Depression Index, and Nowicki-Strickland Locus of Control Scale. Results: The absence of a family confidant was very strongly associated with adolescent self-harm. Despite controlling for a wide range of possible causal factors, poorer parent- adolescent communication remained strongly associated with self-harm. The effect of poorer communication on self-harm was strongest in the group with an internal locus of control. Conclusions: Impairment of communication between adolescents and their parents may be important in the origins of adolescent self-harm.