OBJECTIVES: Among individuals newly treated with oral antidiabetes drugs (AD), to assess the effect of pharmacy loyalty on compliance with AD and on the use of guidelines-recommended medications: 1) ACE inhibitor (ACEi) or angiotensin receptor blocker (ARB); 2) lipid-lowering drug. METHODS: Using Quebec administrative databases we carried out a cohort study of individuals aged ≥18 years who had started an OAD between 2000 and 2006 and for whom we had at least 3 years of follow-up after OAD initiation. Individuals who had filled all their prescriptions in the same pharmacy during the 2^nd year after OAD initiation were considered loyal. Compliance with OAD (Medication Possession Ratio ≥ 80%) and use of an ACEi/ARB and of a lipid-lowering drug were measured in the 3^rd year. Outcomes were assessed using multivariate logistic regressions. RESULTS: Among 97,927 eligible individuals, 64% were loyal to their pharmacy, 64% were compliant with their AD, 64% used an ACEI/ARB and 60% used a lipid-lowering drug. Loyal individuals were more likely to be compliant with their AD (Odds ratio: 1.26; 95% CI: 1.22-1.30), to use an ACEI/ARB (1.17; 1.14-1.21) and to use a lipid-lowering drug (1.15; 1.12-1.18). CONCLUSIONS: Pharmacy loyalty is associated with a better quality of AD use. It is likely due to the fact that pharmacists can better play their role in optimizing their clients’ drug use for patients loyal to their pharmacy as they can then rely on recorded drug use information that is comprehensive.