BackgroundApproximately 50% of rare diseases have symptom onset during childhood. A high level of nursing care and an often uncertain prognosis put caregivers of the affected children at high risk for psychological distress. At the same time, their caregivers have limited access to appropriate psychological care. The aim of this study was to evaluate a web-based psychological support program for caregivers of children with chronic rare diseases (WEP-CARE).MethodsGerman-speaking parents (recruited between May 2016 and March 2018) caring for children aged 0–25 years with a rare disease showing clinically relevant anxiety symptoms, were assigned to either the WEP-CARE (n = 38) or treatment as usual (n = 36) condition within a randomized controlled trial. The primary outcome measure was parental anxiety, assessed with the Generalized Anxiety Disorder Questionnaire (GAD-7). Secondary outcomes were fear of disease progression, depression, coping, quality of life and user satisfaction. The group differences were tested through repeated-measures analyses of variance. The WEP-CARE group was additionally followed up three months after the treatment.ResultsA significant time-group interaction was found for anxiety (F (1,35) = 6.13, p = .016), fear of disease progression (F (1,331) = 18.23, p < .001), depression (F (1,74) = 10.79, p = .002) and coping (F (1,233) = 7.02, p = .010), suggesting superiority of the WEP-CARE group. Sustainability of the treatment gains regarding anxiety, fear of disease progression and coping was confirmed at the 6-month follow-up assessment (p < .01). A significant interaction effect could not be found for quality of life (F(1,2) = 0.016; p = .899). Both participating parents and therapists were satisfied with WEP-CARE.ConclusionsOur results underline the efficacy and feasibility of WEP-CARE for parents of children with various rare diseases.