Conventional manufacturing techniques include removing the excess materials to get the desired shapes; however, additive manufacturing include direct manufacturing of the objects using computer aided design model through adding a layer of material at a time. Strength and durability of the final products are important issues in designing 3D printed functional objects. Primary considerations of 3D printing process include some specifications of the printing process, printing orientation, materials selection and overall design (complexity, size, pore volume and shape). Infill structures are printed in selected patterns with a desired solid percentage, which is arranged using the slicing software. Percent rate and designed pattern are two key parameters for infill specimens which affect the print time, material usage, weight, strength, and decorative assets, as well. Polylactic acid (PLA) is a biodegradable and bioactive thermoplastic derived from renewable resources, such as corn starch, sugarcane, cassava and so on. In this study, five different infill shapes (e.g., solid, diamond, hexagonal, square, and triangle) of PLA were designed using CATIA program, and then 3D printed with 20, 40, 60, 80 and 100 vol.% to determine the effects of the infill shapes on the compressive strengths of the materials. The purpose of this study is to investigate the infill shapes, volumes, and orientation of infill shapes in the 3D printed specimens. Compression test results showed that infill shapes and volume percentages affect the mechanical properties of the 3D printed parts. This study indicated that mechanical properties of 3D printed materials could be maximized using the different infill shapes and volume percentages in 3D printing process.