Overall ageing is associated with a loss of muscle volume and function over time; nevertheless, detailed changes of muscle tissue are incompletely understood. In this preliminary study, magnetic resonance imaging (MRI) was used to assess the effect of age on muscle volume and T2. A cohort of 13 C57Bl/6J Rj male mice was followed from 2.5 to 17 months of age. MRI acquisitions were done at 7 Tesla using a 1H surface cryoprobe. Muscle volume and T2 of the anterior compartment (TA+EDL: tibialis anterior + extensor digitorum longus) were assessed by cross sectional area (CSA) from high-resolution gradient-echo axial images and from a multi-slice multi echo MRI sequence, respectively. Student's paired t test and ANOVA were used for statistical analysis (p < 0.05). Body weight increased up to 12 months and stayed constant until 17 months of age. Muscle volume reached its maximum at 9 months of age. The maximum CSA of TA+EDL muscles, measured on a single slice, decreased significantly from 9 to 17 months of age (8±0.5 mm² at 9 m/o vs 7.1±0.4 mm² at 17 m/o). In parallel, muscle T2 increased significantly from 2.5 to 17 months of age (T2 at 2.5 m/o = 21.5 ±0.2 ms vs T2 at 17 m/o = 22.6±0.3 ms) and from 2.5 to 6 months of age (T2 at 6 m/o = 22.3±0.4 ms). A similar tendency was also observed between 9 and 17 months of age (T2 at 9 m/o = 22± 0.5; p = 0.054). Repeated acquisitions of high-resolution images allowed for longitudinal follow-up of muscle volume from 2.5 up to 17 months of age in mice. The onset of muscle ageing seems to be around 9 months whereas body weight still increases up to 12 months. Muscle T2 increased significantly with age over the timespan of the study. In young ages (2.5 to 6 m/o), T2 increase probably reflects slight changes of histological water compartmentation related to tissue maturation. Ongoing experiments will refine this longitudinal follow-up and provide data at older ages.