Dropout is a frequent problem in face-to-face psychological interventions. However, little is known regarding dropout in computer-based interventions (CBIs). It is important to understand the extent to which children and adolescents drop out of CBIs, so we can ensure that more people complete the programmes to gain maximum benefit. A systematic review of current research on dropout from CBIs identified 15 studies. Dropout rate ranged from 0 per cent to 54 per cent with a median of 15 per cent. There is a need for more rigorous investigation of the extent of, and reasons for, dropout from CBIs with children and adolescents with chronic health conditions.