The current study investigates the Hydroxyapatite (HA) deposition phenomena to the modified surface of tita-nium (Ti) alloy in Hydroxyapatite Powder Mixed Electrical Discharge Machining (HA-PMEDM). Nano and micro size HA powders were mixed into the dielectric liquid and tested for a wide range of pulse currents and pulse-on durations. The change of surface and subsurface properties were evaluated in terms of Surface Roughness (SR), Optical and Scanning Electron Microscopy (SEM), Energy Dispersive Spectrometry (EDS), and X-ray Diffraction (XRD). Finally, in-depth microhardness measurements were carried out to reveal the microhardness profile of the analyzed samples. As a result of the analysis, the effects of the process parameters on the surface roughness, surface topography, and powder deposition to the surface were evaluated. The current results reveal nano and micro powder additives deposited to the surface at different parameters during EDM. The highest rate of HA deposition to the machined surface observed when using 22 A pulse current and 100 mu s pulse-on duration in micro additive dielectric liquid. Resolidified Layer (RL) and Heat Affected Layer (HAL) thicknesses vary between 5 and 50 mu m, 8-83 mu m respectively. Generaly, layer thicknesses in nano HA-PMEDM are higher than the micro HA-PMEDM. The hardness values of the samples machined in nano HA-PMEDM reach 1800 HV on RL. The current results support the use of HA-PMEDM to obtain functional surfaces for medical applications.