Background: Diffuse low-grade gliomas (LGGs) are infiltrative, slow-growing primary brain tumors that remain relatively asymptomatic for long periods of time before progressing to aggressive high-grade gliomas. Methods: We retrospectively identified LGG patients that were stably managed by observation with numerous (≥ 8) serial magnetic resonance imaging (MRI) studies. Tumour volumes were measured by manual segmentation on imaging to study the growth of the lesion. Patient demographic information, tumour characteristics, and histological data were collected from electronic medical records. Results: Of 74 LGG patients, 10 (13.5%) patients were included in the study. The number of MRIs acquired ranged from 8 to 18 (median, 11) over a median of 79.7 months (range, 39.8-113.8 months). Tumor diameter increased at a median rate of 2.17 mm/year in a linear trajectory. Cox regression analysis revealed that initial tumour volume predicted time to clinical intervention, and Mann-Whitney U test found that patients diagnosed prior to age 50 had significantly slower-growing tumors. Clinical intervention was more likely for tumours larger than 73.8 mL. Conclusions: We retrospectively analyzed the natural history of LGGs in patients with numerous serial MRIs managed at a single institution. Comparisons to the literature suggest that this is a subset of particularly slow-growing and low-risk tumours.