Objective: The effect of sand-blasting, acid-etching and anodic-oxidation (SLAO) versus Carbon dioxide laser (Co₂) laser radiation of orthodontic mini-implants (OMIs) is studied to evaluate their primary stability in fresh animal bone blocks. Materials and Methods: 36OMIs from the same manufacturer(Hubit, Gyeonggi-do, Korea);made from Grade 5(Ti-6Al-4V) alloy. They were divided according to methods of their surface treatment into the following groups: group I—No surface treatment, group II—SLAO surface treatment, group III—CO₂ laser irradiation surface treatment. All OMIs were the manually inserted into prepared bone blocks of fresh bovines' femoral bone heads. Primary stability values for OMIs were measured by Periotest^® device and then by Pullout-test device with non-axial forces and at pull-out angle ranged between 15° and 25° to each OMI longitudinal axis. Results: Surface treatment of Grade 5 Ti-6Al-4V alloy OMIs by SLAO achieved the higher primary stability results of pull-out test followed by OMIs with CO₂ laser radiation surface treatment then the machined surface OMIs. Moreover, all OMIs studied groups have no statistically significant difference in perio-test^® values Conclusions: Within the limitations of this study, it can be concluded that :surface treatment of OMIs by each of SLAO and CO₂ laser radiation significantly affected their primary stability in fresh bone blocks.