ObjectivesTo measure adherence in older adults with the use of a novel visual scale screening tool and to compare this adherence measurement with other adherence measures. DesignNoncontrolled prospective intervention trial. SettingGeriatric psychiatry clinic in North Carolina between February 2008 and July 2009. Participants27 geriatric psychiatry clinic patients were identified as meeting eligibility criteria, and 26 of these participants completed the baseline and 3- and 6-month visits. InterventionPharmacist-provided medication management program. Main outcome measuresA novel visual scale, the Medometer, assessed patient adherence to individual medications and aggregate medication regimen. The Medometer was compared with pharmacist subjective adherence assessment and the four-item Morisky scale. ResultsAggregate regimen adherence based on the Morisky scale was 44%, 50%, and 38% at baseline, 3 months, and 6 months, respectively. Similarly it was 48%, 50%, and 46%, respectively, for the aggregate Medometer measurement. Measured individually by drug, average adherence at baseline, 3 months, and 6 months was 44%, 50%, and 35%, respectively, with the Medometer and 74%, 65%, and 50%, respectively, for the pharmacist's subjective assessment. Less stringent definitions for categorizing adherence identified a higher proportion of patients as adherent, with similar trends across measures. Individual medication and aggregate regimen adherence estimates provided face validity for the Medometer, with moderate agreement with other measures. ConclusionThe Medometer is a visual scale that can assess individual medication and overall medication regimen adherence. It performed well in this pilot study, but additional research is needed to assess the reliability and validity of this tool in larger, diverse populations and to test the effectiveness of this tool in guiding pharmacists' efforts to improve medication outcomes.