OBJECTIVES: Cancer patients' anxiety may curb their enrolment in clinical trials (CTs). Thus, the strategies they employ to reduce their anxiety may also determine their enrolment in CTs. The purposes of this study are (1) to compare the anxiety and emotion regulation strategies between patients who are enrolled in CTs (cases) and patients receiving standard cancer treatments who have never taken part in any CT (controls), and (2) to assess the links between these strategies and anxiety. METHODS: In total, 76 cases and 108 controls completed two validated questionnaires assessing their emotion regulation style (ERQ) and anxiety (STAI-Y). RESULTS: Overall, anxiety scores in cases and controls do not differ. The two groups do not differ in regards to their cognitive reappraisal of situations. However, cases inhibit their emotional expressions less than controls. Both cognitive reappraisal and emotional expressions are linked to lower scores of anxiety. CONCLUSIONS: Patients enrolled in CTs do not seem to be more anxious than those receiving a standard treatment. However, cancer patients' anxiety depends on the emotion regulation strategies they use. Emotion regulation during physician-patient interactions should be investigated further as a possible factor for CT enrolment determination.