It is estimated that by the end of the current decade, about 26% of clinker will bereplaced by suitable alternative materials, among which limestone filler probably has the greatest potential due to its wide availability and relatively low price. Although codes allow as much as 35% of clinker to be replaced by limestone filler, the amounts used in practice are far lower and average only 6-7% globally. In order to use the great potential of fillers, it is necessary to know the key parameters thataffect the properties of green concrete with low cement and high filler content in fresh and hardened states. Therefore, thorough literature review was conducted, followed by design of 18 concrete mixtures, in order to analyze the effects of the percentage of cement replacement, water-cement ratio, but also the particle size of the applied filler. The results of experimental research show that at the same w/c ratio there is an increase in compressive strength with increasing percentage of cement replacement and that it is possible to make medium-strength concrete with significantly reduced amount of cement 180 kg/m3 compared to traditional concrete. Thus, economic benefits can be achieved, but also the negative impact of the concrete industry on the environment can be reduced. Unfortunately, the workability of such mixtures can be impaired to the extent that their practical application is prevented, so it is necessary to take further steps to solve this problem.