Objectives: To determine the cell concentration where the differentiation of preadipocytes is most effective, to determine the outcome of various concentrations of adipogenesis induction treatment on the effectiveness of preadipocyte differentiation and determine the time period necessary for maximum differentiation of preadipocytes into mature adipocytes. Study Design: The research is carried out as a randomized control process. Material and Methods: 3T3 L1 cell line derived from mouse preadipocytes were grown in DMEM with added 10% FBS and 1% solution of antibiotics/antimycotics, at a temperature of 37 °C, in a humid atmosphere with 5% CO2. After the cells had grown to the necessary confluency, they were exposed to various concentrations of MDI, a cocktail for induction of the adipogenesis process. Cell grown was monitored on a daily basis and the obtained changes were recorded using the EVOSTM FL Color inverted microscope. For the purpose of determining the differentiation progress of the adipocytes, Trypan Blue staining, Oil Red O staining, MTT analysis and the GSH test were used. Results: The Oil-Red-O staining determined the accumulation of lipid droplets within the cell, which increased in the number and volume with the progress of adipogenesis. The number of differentiated cells decreased in relation to the number of non-differentiated cells, determined using Trypan blue staining which also correlated with the MTT test results. Furthermore, the GSH test was performed to prove that GSH was reduced during the adipogenesis process, which is the result of oxidation stress. Conclusion: The results showed that there was no difference in the effectiveness between various concentrations of agents for induction of the preadipocyte differentiation. When testing adipogenesis on subconfluent and confluent cells, the conclusion is that differentiation is more effective on confluent cells. The most effective differentiation requires following the protocol for differentiation over 12 days.