In this study, change of the apparent resistivity values was investigated on reinforced concrete samples designed with different strength in dry conditions. For this purpose, studies were conducted with 150x150x150 mm cubic samples of 9 different concrete designs. A piece of 10, 14 or 20 mm diameter reinforcement was placed in the middle of concrete samples and 18 samples were prepared for all types of them. Prepared these samples were subjected to the air cure. The apparent resistivity values of the samples were determined by electrical method on different surfaces of the sample at specific time periods of during the 90 days. Furthermore, the concrete strength was determined from average of 3 samples by uniaxial compressive strength test of each sample on 7th, 28th and 90th days. The time dependence change of the apparent resistivity and concrete strength values obtained from these studies was presented. In addition, the relationships between the compressive strengths and the resistivity values were determined separately for each reinforcement diameter. As a result, the apparent resistivity values decrease with increasing concrete compressive strengths in dry conditions concrete of different strengths. This research is a non-destructive approach to determining the strength of concrete in dry condition in-situ and it contributes both time and economically.