Straipsnyje pristatomas dviejų autorių sudarytas Lietuvos mokesčių sistemos vertinimo rodiklių rinkinys, kurį realizavus įvertinta mokesčių sistema. Tikslui pasiekti išanalizuoti esami mokesčių sistemos vertinimo metodai, sudarytas paprastas ir lengvai pritaikomas mokesčių sistemos vertinimo rodiklių rinkinys, kuris yra orientuotas į tris prioritetinius mokesčių sistemos vertinimo aspektus: teisingumą, efektyvumą ir administravimo paprastumą. Apmokestinimo teisingumui įvertinti pasirinkti rodikliai, koncentruoti į pajamų ir išlaidų paskirstymą. Efektyvumui įvertinti pasirinkti rodikliai, orientuoti į mokestinių pajamų surinkimo efektyvumą. Administravimo paprastumą įvertinti turi rodikliai, atskleidžiantys mokestinių pajamų surinkimo, apskaičiavimo ir mokėjimo aspektus. Atliktas mokesčių sistemos vertinimas leido identifikuoti pagrindines problemines Lietuvos mokesčių sistemos vietas ir pateikti siūlymus Lietuvos mokesčių sistemai tobulinti. The paper analyses the opportunities of improving the Lithuanian taxation system by using a simple, easily adaptable and comprehensive set of indicators (V Tanzi's qualifying diagnostic indicators, J. Gill's diagnostic indicators) and focusing on the assessment of its fairness, effectiveness and the ease of tax administration. The Lithuanian taxation system that functioned in 2004–2013 was assessed and some drawbacks were found. Assessing its fairness it was found that, although income distribution in Lithuania exceeded the EU average (10%) and was one of highest, horizontal equity was not implemented: taxpayers receiving similar work-related income were paying different taxes. Speaking about the tax burden it was found that, although its index was significantly lower in Lithuania compared to the EU average, some inequality was identified in tax distribution among work, capital and consumption: the tax burden on work was higher than on capital and consumption added together. Assessing the effectiveness of the taxation system it was found that there were serious problems collecting indirect taxes and handling the shadow economy. Analysing VAT it was found that in 2012–2013 VAT revenues grew almost three times slower than GDP. Comparing the actual and standard tax rates it was found that tax differentiation was insufficient. The biggest gap between the actual and standard tax rates was found in corporate tax. Corporate tax was insufficiently effective for the following reasons: a large number of allowable payments and privileges and tax evasion. Assessing the ease of tax administration it was found that tax regulations were changed several times, became more confusing. The development of IT reduced tax administration costs for both, taxpayers and tax administrators and reached a steady 1.7%. The penalty system was functioning but there were serious problems handling the shadow economy. Drawing on scientific literature overview, a simple, adaptable, comprehensive set of indicators for the assessment of the taxation system focusing on three aspects: fairness, effectiveness and ease of administration is presented in the paper. Fairness of income tax and tax burden, tax collection effectiveness and the ease of tax administration were assessed. It was found that tax collectors had difficulties of tax collection but that was due to taxpayers' dishonesty rather than economic conditions, the penalty system was functioning effectively but serious problems arose handling the shadow economy. Summing up the research results, it should be said that, seeking to improve the Lithuanian taxation system, tax allowances and tax exemptions for various groups of taxpayers should be removed (for example, VAT exemption on heating). However, the removal of tax allowances and the abolition of tax privileges does not guarantee social justice.