This qualitative study explores counsellors' experiences and perceptions of how counselling supervision impacts their clients. The literature review highlights little research in this area. Data collection combined open-ended questionnaires and semi-structured interviews. Analysis was phenomenological incorporating participant validation. The findings indicate that supervision impacts client work both helpfully and unhelpfully. Areas that emerged as having the most direct impact on client work were: exploration of client-counsellor dynamics and raising counsellor self awareness, professional development, emotional support and the quality of the supervisory relationship. Benefits and dangers for clients not taken to supervision were highlighted. Congruence and confidence were the most direct link between supervision and client work.