INTRODUCTION: Biofilm formation differs in accordance to material type and processing technique, which has a crucial impact on maxillofacial prosthetic materials' practicability. OBJECTIVES: to compare the prevalence of the upper respiratory tract and oral microbial flora colonization on the two commercially available forms of polyetheretherketone (modified PEEK); the conventional press form and the CAD-CAM form. MATERIALS AND METHODS: : forty eight circular discs, were processed forming four groups: Group I: twelve BioHPP discs were prepared with CAD-CAM form, Group II: twelve BioHPP discs with conventional press form, Group III: twelve heat polymerized poly methyl meth acrylate (PMMA) to mimic the polished surface Group IV: twelve heat cured PMMA to mimic the fitting surface. Microbiological procedures were performed including microbiological sampling, isolation, purification and identification, biofilm formation and assessment of the normal oral and respiratory flora on modified PEEK and PMMA discs. RESULTS: Acrylic resin fitting surface group had the highest biofilm formation when compared with the three other groups. No statistical significant difference was found between each pair of the three remaining groups, CAD-CAM BioHPP group showed the lowest biofilm formation of all groups according to mathematical data, but it didn't approach the level of being statistically significant. CONCLUSIONS: Both BioHPP processing techniques were positive for biofilm formation, though BioHPP CAD-CAM showed a rougher surface than pressed BioHPP, it showed the least biofilm formation of all groups. Fitting surface of acrylic resin group showed the worst results for biofilm formation