Background According to the Public Health Agency of Sweden, mental ill-health is increasing in Sweden and the affected are becoming younger and younger. There is therefore an increasing need for more research on children and their mental ill-health. To be able to stop this negative development it is of foremost importance that children get help as early as possible. Preschool staff members play a vital role in the identification of mental ill-health among young children and making sure that the right help is given. Aim The aim of the study is to illustrate preschool staff member´s experience of identifying children with mental illhealth. Method The method used is qualitative interview study. Six female preschool staff members have been interviewed and a content analysis has been applied on the answers. Results Children´s mental ill-health is a very complex subject and something that is not included in the Swedish curriculum. Additionally, the education of preschool staff members does not include anything concerning children's mental ill-health. Consequently, preschool staff members battle with a situation where they play a crucial role in the identification of mental ill-health among the children however they do not possess neither the knowledge nor the skills to do so. Conclusion Mental ill-health among children in preschool is a very complex subject. Preschool staff members face a very tough responsibility in identifying the signs of mental ill-health among the children and the reasons for this are many.