Purpose: The purpose of this study was to evaluate the professional time required for the prosthodontic maintenance events of mandibular implant overdentures during the first year of service using three different implant systems (ITI, Steri-Oss, or Southern). Materials and Methods: Seventy-two mandibular implant overdenture patients were allocated to three equal groups, each treated with a different implant system. Data on prosthodontic maintenance events during the first year were categorized and analyzed according to professional time allocation per procedure. Results: The total professional time required to perform all the maintenance events ranged between 29.0 and 34.0 hours and did not differ significantly among the three groups, although there were time differences for matrix activation and replacement. When combining the professional time for all maintenance events for the mandibular overdentures alone, or with the opposing maxillary complete dentures, there were no significant differences between groups. For maintenance of the maxillary dentures, there was an unexplained difference between the Southern group and ITI or Steri-Oss groups (P < .05). Conclusion: The prosthodontic maintenance for mandibular implant overdentures required on average 72 to 98 minutes of professional time per patient during the first year of service, depending on the system used. Int J Prosthodont 2002;15:379–384.