In this paper, a test in a Proctor device is presented as well as the obtained results based on the performed tests.. The test was performed on samples of mechanically - biologically (biodrying) treated mixed municipal waste that were collected in summer and winter from Marišćina, which is – a county center for waste management. The maximum dry waste density that can be achieved is an important piece of information for defining the procedure for installing waste in the body of alandfill, as well as for estimating the lifespan of alandfill regarding its volume. There are two types of Proctor experiments and these are standard and modified Proctor. For the purposes of this paper, the tests were performed in a modified Proctor experiment. The obtained results were compared with the already known compaction results in a standard Proctor experiment and which were obtained on the same type of waste. The main difference between these experiments lies is in the applied compaction energy, which is significantly higher when a modified Proctor test is carried out. Higher compaction energy in itis achieved by using heavier piston weight, larger number of strokes, larger number of layers and heavier piston drop height. Proctor's experiment provides data on humidity at which, in this case, the waste has the highest dry density. The test was performed at 20%, 40%, 60%, 80%, 100% and 120% humidity. The experiment showed that the maximum dry density of 0.79 g/cm3 for the tested waste is achieved at optimum humidity of 55%.