Purpose: This study investigated the effect of metal versus transparent matrix systems on proximal contact tightness (PCT) of class II bulk-fill composite resin restorations. Methods: 80 Ivorine teeth with standardized MO cavity preparations were randomly divided into 4 equal groups (n=20). Group1; sectional metal matrix, group2; pre-contoured circumferential metal matrix in a Tofflemire retainer, group3; conventional metal matrix in a Tofflemire retainer, and group4; Blue Cure-Thru transparent contoured matrix band. All matrices were combined with a separation ring and secured with wooden wedges. Cavity preparations were restored with bulk-fill composite resin; SonicFill 2 with the corresponding bonding system following manufacturer's instructions. Composite material cured for 20s using Elipar S10 light curing unit. Teeth were restored in a clinically relevant situation using KaVo manikin head. After matrix and wedge removal, proximal contact tightness was measured using the Tooth Pressure Meter. Means were calculated and data were statistically-analyzed using ANOVA and Tukey's test (p<.05). Results: Means and standard deviation for proximal contact measurements were: 7.62 (.52), 4.01 (.74), 4.13 (.4) and 2.74 (.37) for groups 1, 2, 3 and 4 respectively. There was a statistical significant difference among all groups except between group2 and 3. Conclusions: Under the conditions of this test, it can be concluded that: 1. Proper proximal contact tightness for bulk-fill posterior composite restorations could be produced by sectional metal matrix rather than transparent matrix. 2. Pre-contoured circumferential metal matrix produced the same proximal contact tightness as conventional metal matrix when both used with a separation ring. Clinical Relevance Transparent matrices couldn't be recommended for bulk-fill posterior com­posite restorations rather than metal matrices