Additive manufacturing is utilized to produce different types of scaffolds to mimic the microcellular structure of bone tissue. Characterizing the biodegradation rate of engineered tissue scaffolds and their respective biodegradation patterns against the 3D structure design of the scaffold is of crucial importance. The research focus of this paper is to understand the relationship between the geometry of biomimetic 3D printed microcellular structures and their biodegradation properties through a comparative experimental assessment study. Polylactic acid (PLA) is one of the commonly used materials in tissue engineering and PLA filaments are widely available for additive manufacturing. To use PLA 3D printed structures as tissue scaffolds, a non-toxicity biological test is conducted using a mammalian cell line, to prove the biocompatibility. Then, multiple common as well as novel microcellular structures are manufactured to assess the effect of the geometry of biomimetic 3D printed scaffolds on the pattern and rate of biodegradation. Microcomputed tomography (Micro-CT) technique is used to monitor the morphology evolution in 3D structures before and after each step of biodegradation. Phosphate buffered saline (PBS) medium plus 5% Carbon Dioxide gas in a CO2 incubator is used to simulate an in vitro environment for performing biodegradation tests. The obtained experimental results are promising as they provide a more advanced understanding on how biodegradation and microcellular structure geometries influence each other; and are helpful for manufacture of optimized biomimetic product for specific needs.