This study sought to evaluate the effects of different staining solutions on the colour stability of nanocomposites compared with microhybrid resin and to evaluate the degree of conversion of these two materials. Two different shades of two different composites were cured in polytetraflouroethylene disk rings. Coffee, tea and cola drinks were used as staining solutions, and distilled water was used as a control. Data were statistically analysed using a paired T-test with a significance level of 5%. Nano composite showed the highest degree of conversion (DC) values based on calculation of the bonded and free carbonyl peak intensities in the spectrum. The colour analysis showed that nanohybrid had the highest ΔE values when exposed to coffee solutions; they showed less color stability despite having a higher degree of conversion. Nano resin composite showed significantly higher discoloration than microhybrid composite.