OBJECTIVE: Clinicians' defence mechanisms are strategies used to manage the stress and the negative affects emerging during a therapy session. The first objective of the study is to adapt the defence mechanisms rating scales (DMRS), originally created by Perry for assessing patient defences, in order to evaluate clinician defences. The second objective is to explore the type of defence mechanisms used by clinicians in oncology. The third objective is to study the sensitivity of the instrument by assessing changes in defensive functioning after specific communication skills training (CST) in oncology. DESIGN: Participants (N=20) were oncology clinicians participating in oncology CST. The defence mechanism rating scales for clinicians (DMRS-C) was used to assess the use of the clinicians' defences before and after CST. RESULTS: The instrument showed promising preliminary psychometric properties. Numerous and very varied defences were coded in each session and corresponding to a great variety of defences. After CST, the clinicians' overall defensive functioning (ODF) increased. Considering the defences' levels, a decrease in the use of immature defences was observed. CONCLUSIONS: Taking into consideration the importance of clinicians' variables in treatment outcome, this instrument constitutes a promising way of assessing the clinician's strategies used to face the emotional difficulties emerging during the therapeutic encounter.