Objective: To evaluate the biofilm adhesion to 4 types of ‘as retrieved’ archwires during orthodontic treatment. To compare biofilm formation by viable cell counting (colony-forming units [CFU]) of microbes ( Staphylococcus aureus, Streptococcus mutans and Candida albicans). Methods: The study was conducted on 40 patients who were divided into 4 equal groups based on the type of archwire of same cross-section (0.019" × 0.025"): group 1—copper-nickel titanium (Cu-NiTi); group 2—titanium molybdenum alloy (TMA); group 3—stainless steel (SS); and group 4—aesthetic coated SS. After 1 month of fixed orthodontic therapy, the archwires were removed carefully from the oral cavity. Results: Biofilm absorbance and biofilm concentration were significant ( P ≤ .05) in all the 4 groups. Conclusion: The group 2 wire showed the maximum affinity for biofilm absorbance and biofilm concentration, whereas the group 4 wire showed the least affinity. The group 4 wire promoted less retention of oral bacteria compared with the wires of the other groups, whereas the group 1 wire showed maximum retention. In the present study, all types of wire showed maximum affinity for S mutans and the least affinity for C albicans, except for the group 1 wire, which showed maximum affinity for S aureus. Biofilm adhesion could be a significant determining factor in the selection of orthodontic archwire for patients primarily at risk of dental caries or periodontal diseases, or both.