Background <p>Low-dose aspirin has long been recommended for primary prevention. This indication has been reconsidered owing to an unfavourable benefit–risk balance, no proven reduction in cardiovascular risk and an increase in the risk of haemorrhage. The recommendations concerning this indication are still contradictory and are a source of confusion for general practitioners (GPs), especially in the management of patients over 70 years of age who are at greater risk of complications. We explored the determinants of the decision-making behaviour of general practitioners regarding aspirin for primary prevention in patients aged 70 years and older.</p> Methods <p>Grounded theory was the basis of this qualitative study, which involved individual semistructured interviews with GPs in the Auvergia region. The interviews were recorded and analysed by two researchers.</p> Results <p>Twelve GPs were interviewed, and 4 themes were observed. The distinction between primary and secondary prevention was unclear, particularly for patients with diabetes or asymptomatic atheromatous lesions. Cardiovascular risk was assessed using a standardized approach rather than a risk scoring tool. GPs considered physiological age rather than chronological age when assessing the benefits and risks associated with regular low-dose aspirin use. In the end, the opinion of the specialist and that of the patient were paramount in decision-making.</p> Conclusion <p>Our study provides a better understanding of the determinants of GPs’ decision-making in the prescription of aspirin for primary prevention in elderly patients. This occurs in a context of uncertainty and is a source of ambivalence; thus, a clear recommendation would be beneficial.</p>