Objectives: The purpose of the study was to get new insights into stability of optical properties; colour, lightness, chromaticity and translucency of glass-ceramic materials in a corrosive medium. Materials and methods: Three specimens (plates of 10 mm × 12 mm × 0.8 mm) of each type of IPS e.max ceramics (Ivoclar Vivadent, Schaan, Liechtenstein) were made in three colours (A2, C2 and B3) by three fabrication techniques (layering – IPS e.max Ceram Dentin; heat-pressing – IPS e.max Press; CAD/CAM – IPS e.max CAD). Three acrylic specimens (PMMA) of the same dimensions (Ivoclar Vivadent, Schaan, Liechtenstein) were also made in 3 colours (130, 410, 310). The comparison is made with the standard Vitapan Classical shade guide (Vita Zahnfabrik, Bad Säckingen, Germany). CIE L*a*b* values were measured by a spectrophotometer (X-Rite DTP 20 Pulse, Neu Isenburg, Germany) to calculate the difference in colour (ΔE*), chromaticity (ΔC*) of translucency parameter (TP values) before and after exposure to 4% acetic acid at 80 °C for 16 hours (ISO 6872). Statistical data were analysed using the IBM SPSS 22 software. Results: Optical properties by which analysed materials and colours differ the most are deviation from chromaticity and lightness from the standard. Before corrosion IPS e.max Ceram Dentin has greater chromaticity deviation from the standard, and IPS e.max Press and CAD lower (p<0,05). IPS Ceram Dentin has the highest lightness in the colour B3, and the lowest chromaticity for the colour C2. For IPS e.max Press and CAD, the highest lightness values have A2 specimens, and the lowest ones are for the colour C2, the highest chromaticity values are for the colour B3 and the lowest ones for the colour A2. Translucency is the highest for the colour B3 (p=0,007), and the lowest for the colour A2 of IPS e.max Press and Ceram Dentin (p=0,028), and for CAD there is no difference. In the analysis of the technology, specimens fabricated by layering technique (IPS e.max Ceram Dentin) have higher chromaticity in all three colours and the lowest translucency. Specimens fabricated by computer-aided manufacturing (IPS e.max CAD) have the highest translucency. Lightness is significantly lower for specimens fabricated by layering technique in the colours A2 and C2, and higher for the colour B3. Exposure to a corrosive medium diminishes chromaticity, which is significant for IPS e.max Press and IPS e.max CAD in all colours, and for Ceram Dentin only in the colour B3. Corrosion does not affect the change of colour and lightness and there is no diminution of translucency, except for the colour B3 IPS e.max CAD. Acrylic specimens have showed the biggest deviations of all optical properties before and after corrosion. There is no significant change of roughness as a result of exposure to acetic acid. Conclusion: Corrosion affects chromaticity properties and partly translucency of glass-ceramics.