Past experimental researches showed that as the beam depth increases, there is arnsignificant decrease on the shear stress capacity of reinforced concrete beams withoutrnshear reinforcement. This trend is called size effect. Since most beams contain at leastrnminimum shear reinforcement as required by building codes, it is also important to studyrnsize effect on reinforced concrete beams with shear reinforcement. In this paperrnexperimental and analytical investigations were made to study size effect on shearrnbehavior of reinforced concrete beams with shear reinforcement. All parametersrninfluencing shear capacity of beam were held constant except beam depth and shearrnreinforcement ratio. Six reinforced concrete beam specimens tested in laboratory andrntwelve beam specimens analyzed by VecTor2 nonlinear finite element software.rnExperimental results showed that for beams without shear reinforcement the shear stressrncapacity decreased by 9.3%, on the other hand, for beams which have shearrnreinforcement with ratio of 0.14% the shear stress capacity decreased by only 3.8%,rnwhen the beam height raised from 240mm to 360mm. Analytical results also showed thatrnwhen depth of the specimen increased from 240mm to 1200mm, the shear stress capacityrndecreased by 58.2% for beam specimens without shear reinforcement and by 48.9% forrnbeam specimens with 0.14% ratio of shear reinforcement. From both results it can bernconcluded that even if using shear reinforcement minimize size effect, they cannotrneliminate size effect completely. The comparison made among experimental, code-basedrnand analytical predictions showed that Eurocode 2 and ACI 318-19 shear provisionsrngave generally good estimates of shear capacity for al1 analyzed specimens. However,rnthe ACI 318-14 shear provision overestimate shear capacity of reinforced concreternbeams when depth of beams exceeds 800mm that is because it did not consider sizerneffect, so that, the decision made by ACI committee to replace it by new equation in ACIrn318-19 which consider effect of member depth is correct.