Background: Published data on prostate magnetic resonance imaging (MRI) during follow-up of men on active surveillance are lacking. Current guidelines for prostate MRI reporting concentrate on prostate cancer (PCa) detection and staging. A standardised approach to prostate MRI reporting for active surveillance will facilitate the robust collection of evidence in this newly developing area. Objective: To develop preliminary recommendations for reporting of individual MRI studies in men on active surveillance and for researchers reporting the outcomes of cohorts of men having MRI on active surveillance. Design, setting, and participants: The RAND/UCLA Appropriateness Method was used. Experts in urology, radiology, and radiation oncology developed a set of 394 statements relevant to prostate MRI reporting in men on active surveillance for PCa. Each statement was scored for agreement on a 9-point scale by each panellist prior to a panel meeting. Each statement was discussed and rescored at the meeting. Outcome measurements and statistical analysis: Measures of agreement and consensus were calculated for each statement. The most important statements, derived from both group discussion and scores of agreement and consensus, were used to create the Prostate Cancer Radiological Estimation of Change in Sequential Evaluation (PRECISE) checklist and case report form. Results and limitations: Key recommendations include reporting the index lesion size using absolute values at baseline and at each subsequent MRI. Radiologists should assess the likelihood of true change over time (ie, change in size or change in lesion characteristics on one or more sequences) on a 1-5 scale. A checklist of items for reporting a cohort of men on active surveillance was developed. These items were developed based on expert consensus in many areas in which data are lacking, and they are expected to develop and change as evidence is accrued. Conclusions: The PRECISE recommendations are designed to facilitate the development of a robust evidence database for documenting changes in prostate MRI findings over time of men on active surveillance. If used, they will facilitate data collection to distinguish measurement error and natural variability in MRI appearances from true radiologic progression. Patient summary: Few published reports are available on how to use and interpret magnetic resonance imaging for men on active surveillance for prostate cancer. The PRECISE panel recommends that data should be collected in a standardised manner so that natural variation in the appearance and measurement of cancer over time can be distinguished from changes indicating significant tumour progression. The Prostate Cancer Radiological Estimation of Change in Sequential Evaluation panel recommends that prostate magnetic resonance imaging reports for men on active surveillance include index lesion size in absolute values at each time point and an estimation of the likelihood of significant change between baseline and current images. © 2016 European Association of Urology.