ISSUE ADDRESSED: Women with a history of gestational diabetes mellitus (GDM) have an increased risk of developing type 2 diabetes mellitus (T2DM). Regular physical activity plays an important role in preventing T2DM. This study aimed to explore the perceptions of physical activity among women with previous GDM, in the context of preventing T2DM. METHODS: Individual semi-structured interviews were conducted with 10 women with previous GDM who had not been diagnosed with T2DM. Data were analysed using a modified grounded theory approach. RESULTS: Women perceived diet to be significantly more important for the prevention of T2DM than physical activity. They underestimated the role of physical activity in preventing diabetes, which may have resulted from the lack of information they received following their pregnancy. Women consistently placed the needs of their families before their own, despite acknowledging their future health risks. The most commonly cited constraints on physical activity participation were lack of time, partner support, and appropriate childcare. They identified a need for 'family-friendly' community-based physical activity programs for mothers, more accessible childcare, and more information about the role of physical activity in diabetes prevention. CONCLUSIONS: Awareness of the role of physical activity for the prevention of diabetes was low. Physical activity promotion for women with previous GDM needs to be shaped around the opportunities and constraints identified by this population group.