The application of nanoparticles (NPs) has attracted considerable attention as targeted delivery systems. CaCO3 has become the focus due to its advantages including affordability, low toxicity, biocompatibility, cytocompatibility, pH sensitivity and sedate biodegradability and environment friendly materials. In this article, we will discuss the po- tential roles of CaCO3-NPs in three major therapeutic applications; as antimicrobial, for drug delivery, and as gene delivery nanocarrier.