Objective: To assess posttraumatic stress (PTS) symptoms in adolescents with and without asthma and their parents and the relationship between PTS symptoms and asthma morbidity. Method: Three groups of adolescents (12-18 years) participated: adolescents who had experienced a life-threatening asthma episode (n = 49), asthma controls (n = 71), and healthy controls (n = 80). Adolescents completed the UCLA PTSD Reaction Index, Multidimensional Anxiety Scale for Children, and Reynolds Depression Inventory. Parents completed the Impact of Events Scale-Revised, Brief Symptom Inventory, and Asthma Functional Morbidity Scale. Results: Twenty percent of adolescents with life-threatening asthma met criteria for PTSD compared with 11% of the asthma controls and 8% of the normal controls. Twenty-nine percent of parents of adolescents with life-threatening asthma met criteria for PTSD compared with 14% of parents of asthma controls and 2% of normal controls. Adolescent PTS symptoms accounted for 5% of the variance in functional asthma morbidity even after controlling for disease severity and other anxiety and depressive symptoms ([beta] = 0.26). Conclusions: Adolescents with asthma and their parents, particularly those who have experienced a life-threatening event, have high levels of PTS symptoms that are linked to asthma morbidity. Interventions to improve asthma outcomes should include assessment and treatment of trauma and PTS symptoms. (Contains 3 tables.)