BACKGROUND Different pharmaceutical forms of oral tacrolimus allow tailored administration. The granular formulation facilitates accurate dose adjustment of tacrolimus according to patient characteristics, such as weight, or potential concomitant drug interactions. Currently, there are no data describing the use of tacrolimus granules in transplant recipients in France. MATERIAL AND METHODS OPTIMOD was a 6-month prospective, observational multicenter study that aimed to describe patient characteristics and conditions of use of tacrolimus granules. The 25 participating centers enrolled patients at time of tacrolimus granules initiation and were to collect patient and treatment data at initiation and after 6 months of follow-up. All analyses were descriptive. RESULTS Of 61 patients included, 55.7% were children (mainly kidney graft recipients) and 44.3% were adults (mostly lung graft recipients). Overall, 24.6% of patients (all children) initiated tacrolimus granules immediately post-transplant; the remaining 75.4% converted to tacrolimus granules from ciclosporin or immediate-release tacrolimus hard capsules. The main reasons for initiating tacrolimus granules, irrespective of whether first- or second-line therapy, were to offset potential drug-drug interactions in adults by adjusting dose, and to adapt to the particular needs of children as patients. Most patients (78.7%) underwent ≥1 dose modification during follow-up. Eleven rejection episodes occurred during follow-up, of which none led to graft loss. The adverse-event profile of the tacrolimus granules was similar to that of other tacrolimus formulations and 7 treatment-related adverse events were recorded. CONCLUSIONS Results suggest that tacrolimus granules are well tolerated and effective in preventing transplant rejection when administered in routine practice in France.