Statement of problem. Monolithic zirconia can be influenced by the underlying titanium base which alters the restoration shade and creates unsatisfactory optical results. Purpose. The purpose of this in vitro study is to find out the influence of zirconia opaquer on the optical proportion of monolithic zirconia at different thicknesses. Material and methods. Three experimental groups have been examined - monolithic zirconia, zirconia opaquer and titanium implant abutment (group A), monolithic zirconia and titanium implant abutment (group B) and monolithic zirconia only (group C). Experimental specimens with a thickness of 0.8 mm, 1.5 mm, 2 mm were designed for a titanium implant abutment and 12 monolithic zirconia specimens for each thickness in shade A2 were prepared for each group respectively. A digital spectrophotometer was used to record the components for color value, chroma and hue. The mean and standard deviation (SD) of these measurements were calculated for all groups. The data for three independent groups were analyzed using the Kruskal-Wallis test and compared pairwise using Dunn’s post hoc test adjusted by the Bonferroni correction. The degree of statistical significance was considered P<0.05. Results. Statistically significant differences were found in all components of color value (L), chroma (C), hue (H) and thickness across groups A, B and C. For 0.8 mm thickness, the post-hoc test showed no significant difference between group A and C for the L and H color components. However statistically significant differences were found between groups B and C for all color components L, C, and H. For 1.5 and 2 mm thickness, the post-hoc test shows no significant difference between group B and C in all color components L, C and H. Statistically significant differences were found between group A and C for all color components L, C and H. Conclusions. By increasing the thickness of monolithic zirconia, better masking color effect of the metal abutment background can be achieved. Using the monolithic zirconia on thin thickness (less than 1 mm) alone, without zirconia opaquer or opaque cement, cannot optimally mask the metal abutment background color. However, using the zirconia opaquer on thin monolithic zirconia thickness (less than 1 mm) can positively affect the final shade by masking the metal abutment background. Monolithic zirconia in thickness 1.5 and 2 mm can alone mask the metal abutment background color, while using the zirconia opaquer here can negatively affect the final shade of the restoration.