The practice style variation (PSV) incurs undesirable clinical and economic consequences for patients and the healthcare system. This review aims to analyze the economic consequences of PSV in medical interventions. A comprehensive electronic search was conducted through PubMed, Web of Sciences, EBSCO, EMBASE, and Cochrane databases to retrieve studies on economic consequences of PSV within 1975–2018. The studies were independently assessed by two reviewers. The quality of studies was assessed by Strengthening the Reporting of Observational Studies in Epidemiology checklist. No language restriction was applied. Only four studies met the eligibility criteria. These studies have been conducted retrospectively in developed countries. Most of the included studies used consumer demand theory to measure the economic consequences of PSV. Findings showed 12%–74% of all variations in healthcare services are related to PSV, thereby incurring up to 23 million dollars for the healthcare system. The PSV is related to the total expenditure, price elasticity, and coefficient of variation of healthcare services. PSV associated with huge inefficiency and inequity in access to healthcare services. To mitigate the consequences of PSV, policymakers should consider PSV in both developing the medical education plans as well as cost management. Using multilevel analysis to investigate the determinants of PSV would be beneficial.