STUDY QUESTION What is the effect of the positive reappraisal coping intervention (PRCI) on anxiety in women awaiting the outcome of an IVF/ICSI cycle? SUMMARY ANSWER Women reported significantly more anxiety during the waiting period than before treatment, but the use of the PRCI did not significantly reduce anxiety during the waiting period. WHAT IS KNOWN ALREADY Waiting for the outcome of IVF/ICSI treatment after embryo transfer is one of the most stressful periods of fertility treatments. At present, no evidence-based coping interventions are available to assist women though this waiting period. The PRCI has been designed to address this unmet need by promoting positive reappraisal coping. STUDY DESIGN, SIZE, DURATION A three-armed randomized controlled trail (RCT) was designed to evaluate the PRCI in women undergoing IVF/ICSI. Data were collected between October 2010 and June 2012. A total of 377 participants were randomized to receive either the PRCI and emotional monitoring, emotional monitoring only, or routine care. Only the PRCI-monitoring group received the coping intervention, comprising an explanatory leaflet and ten statements to be read at least once in the morning and once in the evening. PARTICIPANT, MATERIALS, SETTING, METHODS To capture the general impact of the PRCI, all three groups completed questionnaires at three time points: just before the waiting period (time 1: stimulation phase), on Day 10 of the 14-day waiting period (time 2: waiting period) and 6 weeks after the start of the waiting period (time 3: 6-week follow-up). In addition, to capture the specific impacts of the PRCI on the days of the waiting period, the PRCI-monitoring group and the monitoring-control group also rated their emotions and reactions daily, for the 14-day waiting period. MAIN RESULTS AND THE ROLE OF CHANCE Of the women who agreed to participate and who met eligibility criteria, 377 were randomized. All study participants reported significantly more anxiety and depression during the waiting period than before treatment (P < 0.001). The mean difference in anxiety between time 1 versus time 2 was 1.465 (95% CI 1.098-1.832). The mean difference in depression between time 1 versus time 2 was 0.514 (95% CI 0.215-0.813). Use of the PRCI did not significantly reduce anxiety or depression, or daily negative emotions during the waiting period. However, patients randomized to the PRCI reported significantly more positive emotions during the waiting period (P < 0.001) than the monitoring-control group, and reported the intervention to be easy to use, and as having a positive psychological effect. No significant differences were found between the groups in treatment outcome. LIMITATIONS, REASONS FOR CAUTION The lack of difference observed in the present study for anxiety levels between the PRCI and the monitoring-control group could have been due to the effects of monitoring itself or its ability to attenuate or obscure the effects of the PRCI intervention in unknown ways. A randomized group of women who used only the PRCI without daily monitoring would provide more insight. WIDER IMPLICATIONS OF THE FINDINGS The PRCI was shown to help women reinterpret the demands of the waiting period in a more positive way. These results are consistent with previous studies showing that positive reappraisal coping is a useful strategy for unpredictable and uncontrollable situations represented by a medical waiting period. This simple low cost self-help coping intervention increases positive affect during the waiting period in an IVF/ICSI treatment. STUDY FUNDING/COMPETENT INTEREST(S) The Women and Baby Division of the University Medical Centre Utrecht funded the study. The authors have no conflicting interest(s). TRIAL REGISTRATION NUMBER The study is registered at the Clinical Tials.gov (NCT01701011).