Objective: Multimorbidity and complex medications increase the risk of medication-related problems, especially in vulnerable home care patients. The objective of this study was to examine whether inter professional medication assessment has an effect on medication quality among home care patients. Design: The FIMA (Finnish Interprofessional Medication Assessment) study was a randomized, controlled study comparing physician-led interprofessional medication assessment and usual care. Setting and Participants: The FIMA study was conducted in home care settings in Finland. The participants were >= 65-year-old home care patients with >6 drugs daily, dizziness, orthostatic hypotension, or a recent fall. Methods: Primary outcome measures over the 6-month follow-up were number of drugs, drug-drug interactions, medication-related risk loads, and use of potentially inappropriate medications (PIMs) examined by SFINX, RENBASE, PHARAO, and Meds75+ databases. The databases classified information as follows: A (no known pharmacologic or clinical basis for an increased risk), B (evidence not available/uncertain), C (moderately increased risk which may have clinical relevance), and D (high risk, best to avoid). Logistic regression adjusted for age, sex, and the baseline level of the outcome measure served as statistical methods. Results: The mean number of all drugs for home care patients (n = 512) was 15. The odds of drug-induced impairment of renal function (RENBASE D, P = .020) and medication-related risk loads for bleeding (PHARAO D, P = .001), anticholinergic effects (PHARAO D, P = .009), and constipation (PHARAO D, P = .003) decreased significantly in the intervention group compared with usual care. The intervention also reduced the odds of using PIMs (Meds75+ D, P = .005). There were no significant changes in drug drug-interactions or number of drugs. Conclusions and Implications: FIMA intervention improved the medication quality of home care patients. Risks for renal failure, anticholinergic effects, bleeding, constipation, and the use of PIMs were reduced significantly. (C) 2020 The Author(s). Published by Elsevier Inc. on behalf of AMDA - The Society for Post-Acute and Long-Term Care Medicine. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).