This paper presents a methodology for the contribution of demand response in reducing the cost of voltage control in radial distribution grid with distributed generators (DG). The bidirectional power flow in the active distribution network can introduce voltage issues that impede the integration of DG. Due to this fact, the distribution system operator (DSO) has to enhance the lines in the grid or curtail the power output of DG in case of constraint. The possibility of using the flexibility of demand to cope with the voltage constraint is investigated in this paper. The results are promising that by using the demand response, it is able to reduce the active curtailment of DG and postpone the investment of grid reinforcement.