Silicon nitride (Si3N4) has excellent biocompatibility in vivo, partial radiolucent implant material on radiographic imaging, antibacterial properties, along with attractive metallurgical and mechanical characteristics. Manufacturing intricate Si3N4 components through conventional techniques presents a significant challenge due to its elevated physical and mechanical properties. Biomedical implants require complex, freeform architecture with graded porosity to fit into patient anatomy. Additive bioceramics manufacturing has been recognized as a potential solution to the problems raised by biological implants for bone deformity treatment due to limited bone supply and the risk of pathogen transmission or immunological rejection. Direct ink writing (DIW) is a type of additive manufacturing that has gained considerable popularity in the recent years due to its ability to fabricate near-net anatomical shapes. However, the fabrication of highly dense ceramics using DIW is still constrained by certain limitations, primarily due to the numerous challenges involved in the development of suitable feedstock. This article summarizes the current research on DIW of medical-grade Si3N4. It begins with literature on the properties of Si3N4 and its potential applications in medical devices. Then, this review discusses binders and dispersants for developing inks with improved rheological properties to achieve high printing resolution with accuracy, together with in situ sintering of Si3N4 green parts to achieve high density and strength. Finally, Si3N4 bioceramics and their bioactivity, osteogenesis, density, fracture toughness and strength are also explored to achieve the ideal properties for their application in the human body.