The mechanisms responsible for modifying the wettability characteristics of a magnesia partially stabilised zirconia (MgO-PSZ) bioceramic material after CO2 laser treatment have been elucidated. Changes in the contact angle, θ, and hence the wettability characteristics of the MgO-PSZ were attributed primarily to: modifications to the surface roughness of the material which accordingly effected reductions in 9, the increase in the surface O2 content of the material; since an increase in surface O2 content intrinsically brings about a decrease in 9, and vice versa, and the increase in the polar component of the surface energy, Ø due to the CO2 laser induced surface melting and resolidification which consequently created a partially vitrified micro structure that was seen to augment the wetting action. However, the degree of influence exerted by each mechanism was found to differ markedly. Isolation of each of these mechanisms permitted the magnitude of their influence to be qualitatively determined. Surface energy, by way of microstructural changes, was found to be by far the most predominant element governing the wetting characteristics of the MgO-PSZ. To a much lesser extent, surface O2 content, was also seen to influence to a change in the wettability characteristics of the MgO-PSZ, whilst surface roughness was found to play a minor role in inducing changes in the wettability characteristics.