Nine therapists were interviewed regarding their reactions to children displaying sexually problematic behaviour and how they managed these reactions. The framework of countertransference was used to understand therapists' reactions. Data were analysed using inductive thematic analysis. The participants reported a wide range of powerful and intense reactions including powerlessness, feeling deskilled, fear, shock, having sexual feelings and feeling like an abuser. They described a number of personal changes in themselves including personal growth and becoming less trusting. They also reported using various personal and professional resources to manage their reactions. Working with children displaying sexually problematic behaviour can evoke powerful reactions in therapists and other professionals who work with these children. It is therefore important to raise awareness of the impact of working with these children and normalise therapists' experiences so that they can be more open and active in seeking support when needed. Further implications for practice and future research are also discussed.