Abstract Background Paediatric obsessive-compulsive disorder (OCD) is a chronic condition often associated with severe disruptions of family functioning, impairment of peer relationships and academic performance. Mean age of onset of juvenile OCD is 10.3 years; however, reports on young children with OCD show that the disorder can manifest itself at an earlier age. Both an earlier age of onset and a longer duration of illness have been associated with increased persistence of OCD. There seems to be difficulty for health professionals to recognize and diagnose OCD in young children appropriately, which in turn may prolong the interval between help seeking and receiving an adequate diagnosis and treatment. The objective of this study is to enhance knowledge about the clinical presentation, diagnosis and possible treatment of OCD in very young children. Case presentation We describe a prospective 6 month follow-up of five cases of OCD in very young children (between 4 and 5 years old). At the moment of first presentation, all children were so severely impaired that attendance of compulsory Kindergarten was uncertain. Parents were deeply involved in accommodating their child’s rituals. Because of the children’s young age, medication was not indicated. Therefore, a minimal CBT intervention for parents was offered, mainly focusing on reducing family accommodation. Parents were asked to bring video tapes of critical situations that were watched together. They were coached to reduce family accommodation for OCD, while enhancing praise and reward for adequate behaviors of the child. CY-BOCS scores at the beginning and after 3 months show an impressive decline in OCD severity that remained stable after 6 months. At 3 months follow-up, all children were able to attend Kindergarten daily, and at 6 months follow-up, every child was admitted to the next level / class. Conclusions Disseminating knowledge about the clinical presentation, diagnosis and treatment of early OCD may shorten the long delay between first OCD symptoms and disease-specific treatment that is reported as main predictor for persistent OCD.