Purpose- Over the years, the Financial Accounting Standards Board (FASB) and International Accounting The Standards Board (IASB) has made numerous amendments to controversial lease accounting rules. In order to increase transparency and comparability, IFRS 16 Leases Standard published by the IASB will be implemented as of January 1, 2019. Operating leases will require capitalization in accordance with this standard. The purpose of this paper is to analyze the impact of the new leasing standard on the financial statements and ratios of the firms and industries represented in the BIST 100 indice under a variety of assumptions. Methodology- The financial statements and disclosures of the 63 non-financial companies listed in BIST 100 are investigated. Under various assumptions; the effect of IFRS 16 on the financial statements are measured. In this context, it was assumed in 2017, companies used IFRS 16 instead of IAS 17. The related accounts are recalculated accordingly. Thus, it is possible to see the effect on the financial statements and financial statements items according to IAS 17 and IFRS 16. Findings- As a result of the calculations and analysis, decrease in profit for the period; and increase in operating profit before financial income/expense, operating profit, financial expenses, total assets and total labilities are determined. Conclusion- With the adoption of IFRS 16, the rights and liabilities related to the operating leases will be reported on the balance sheet. In this way, the comparability will increase and financial ratios will become more significant. This will also have an impact on strengthening the fair presentation of the financial statements.