Multiparametric MRI features heavily on a number of active surveillance protocols. This study looked at 86 men on active surveillance who had an mpMRI prior to 2013 to assess how lesions changed over time. Two blinded radiologists examined all the scans, measuring lesions and attributing a five-point Likert score for the most conspicuous (index) tumour. They demonstrated that 17% of men with no visible lesion developed a visible lesion at a median follow-up of 3.6 years. It is possible to demonstrate size increase with serial scans, however, the variability in volume measurements means that this is far from reliable. Whilst this is a small study, its findings will help identify the optimal timing between follow-up scans and the utility of their findings in patients on active surveillance.