Apatite-mullite glass-ceramics have been developed as an alternative to hydroxyapatite for use in vivo as a bioactive, osseoconductive biomedical alloy coating. In the cerammed state, they present a number of advantages including control over dissolution rates and mechanical properties by altering the composition of the parent glass or heat treatment regime. In the present study, a simple sedimentation route was used to coat a biomedical titanium alloy, commonly used for orthopaedic applications. The material was deposited as a glass and cerammed in situ to create a well adheared coating that resisted delamination or cracking. To investigate the nature of the coating-substrate reaction, a number of characterization techniques were used to examine the crystallization behaviour of the glass, the glass-ceramic microstructure, and the interfacial reaction region composition. The presence of products such as titanium silicides and unexpected pores are explained by proposed reaction routes between the titanium and glass coating.