© 2018 Turkish Biochemistry Society. All rights reserved.Aim: This study was evaluated the effects of N-acetylcysteine (NAC) and calcium hydroxide (Ca(OH)2) on the expression levels of matrix metalloproteinase -2, -9 (MMP-2, -9) and tissue inhibitor metalloproteinase -1, -2 (TIMP-1, -2) in lipopolysaccharide (LPS)-stimulated human macrophages. Methods: Human monocyte precursor cells (THP-1) were differentiated into macrophage-adherent cells and were stimulated with LPS for 24 h. Then individually incubated with NAC or Ca(OH)2 for 24, 48 and 72 h. Following incubation, protein expression and mRNA levels of MMP-2, -9 and TIMP-1, -2 were evaluated using enzyme-linked immunosorbent assay (ELISA) and quantitative real-time polymerase chain reaction (qRT-PCR). Data were statistically analysed using two-way ANOVA, to followed by Bonferroni test at α = 0.05. Results: NAC significantly decreased mRNA expression and protein levels of MMP-9, while Ca(OH)2 decreased mRNA expression alone at 24 h. NAC and Ca(OH)2 decreased mRNA expression of MMP-2 at 24 h, while NAC increased this expression at 48 h. Although NAC and Ca(OH)2 decreased the mRNA expression of TIMP-1, -2 at 24 h, only NAC increased mRNA expression of TIMP-1 at 48 h. Conclusion: At the early stages of inflammation, NAC and Ca(OH)2 have anti-inflammatory effects on macrophages.