This study used the Andersen Model for Health Services Utilization to examine a pharmacist-provided telephone MTM program among Medicare Part D beneficiaries. Predisposing (age, gender, race) and need factors (number of medications, number of chronic diseases, medication regimen complexity) were assessed. The health behavior, MTM utilization, distinguished the intervention and control groups. The health outcomes were change in number of medication-related problems, change in medication adherence [using the medication possession ratio (MPR)], and change in total drug costs. Medication knowledge, medication adherence (using the Morisky Scale), and patient satisfaction were also measured in the intervention group. The intervention and control groups were not significantly different in age (71.2 ± 7.5 vs. 73.9 ± 8.0 years), number of medications (13.0 ± 3.2 vs. 13.2 ± 3.4), number of chronic diseases (6.5 ± 2.3 vs. 7.0 ± 2.1), and medication regimen complexity [21.5 (range 8 – 43) vs. 22.8 (range 9 – 42.5)], respectively. For the subset of problems that was evaluated in the intervention and control groups, 4.8 (± 2.7) and 9.2 (± 2.9) problems were identified at baseline and 2.7 (± 2.3) and 8.6 (± 2.9) problems remained at the 3-month follow-up, respectively. Cost-related and preventative care needs and drug-drug interactions were the three most common problems identified. Multivariate regression analysis revealed that the intervention group had significantly more problems resolved (p < 0.0001) when compared to the control group, while controlling for predisposing and need factors. Significantly fewer problems were resolved (p = 0.01) as number of diseases increased and significantly more problems were resolved (p = 0.01) as medication regimen complexity increased. There were no significant predictors of change in MPR or total drug costs from baseline to the 3-month follow-up. Medication knowledge and medication adherence measured by the Morisky scale did not change significantly from baseline to the 2-week follow-up. However, patients were very satisfied with the service. A pharmacist-provided telephone MTM program was an effective method for identifying and resolving medication and health-related problems. A longer follow-up period may be necessary to detect the impact of pharmacist provision of MTM on adherence, total drug costs, and knowledge. / text