The article reports ways and trends in polylactide (PLA) modification methods concerning literature data. The paper consists of two parts and presents the process of polylactide production, and the connection of changes in its properties with the polymer structure obtained thanks to appropriate process conditions and methods of its final polymer properties improvement. Discussing both the most advantageous properties and disadvantages, the possibilities of increasing the scope of its applicability in reference to selected modification methods were presented and discussed. The presented research results related to various modification methods arrange the knowledge from the discussed scope, indicating the best possible effects and limitations. The most considerable emphasis is on the methods and results obtained from heterogeneous nucleation and incorporating various fillers in the PLA matrix. The other methods, like applying chemical interaction methods (crosslinking, using chain extenders), development of polymer blends, copolymerization, and plasticization, are presented synthetically. In summary, the review present and organizes the achievements in the possibility of modifying the most prospective biodegradable polymer, which is PLA.