OBJECTIVES: Community pharmacies focused on HIV offer enhanced services to assist patients taking antiretrovirals (ARV), yet the impact of these services is unclear.  The objective of this study was to determine differences in patient characteristics, regimen characteristics, and regimen refill adherence for HIV-SP versus NSP users.  METHODS: We conducted a retrospective database study of patients with ARV claims from May 2007 – August 2009 at California Walgreens pharmacies. A modified medication possession ratio (mMPR) was used to calculate regimen refill adherence.  Patients were deemed “regimen adherent” on any given study day if they possessed three or more antiretroviral drugs that included:  a protease inhibitor, a non-nucleoside reverse transcriptase inhibitor, raltegravir, an entry inhibitor, abacavir, or tenofovir.  A patient’s regimen adherent days were summed, then divided by the total number of study days contributed to calculate the mMPR.  A multivariable logistic regression model was constructed to determine independent factors which contributed to having > 95% regimen refill adherence.   RESULTS: 4254 HIV-SP and 11679 NSP users were included.  Compared to NSP users, HIV-SP users traveled farther to their pharmacies (5.03 vs. 1.26 miles), filled more chronic disease medications (35% vs. 30%) and psychotropics (42% vs. 39%), and received more fixed dose combination (FDC) ARVs (92% vs. 83%;); all p <0.01.  Median regimen mMPR was higher for HIV-SP users (90% vs. 77%, p <0.0001).  After adjustment for various factors, both the use of HIV-SP (OR= 1.79, 95% CI 1.72-2.08) and fixed dose combination ARV tablets (OR=3.3, 95% CI 2.86-4.01) were associated with a greater likelihood of having >95% regimen refill adherence.  CONCLUSIONS: Patients filling their prescriptions at HIV-SP are more likely to use fixed dose combination ARV and have higher regimen refill adherence; particularly those taking FDCs.  HIV-SP should be further explored to determine whether specific services improve patient adherence.