Purpose: This article compares the cost of mandibular two-implant overdenture treatment to that of conventional denture treatment in an academic teaching hospital. Materials and Methods: Sixty edentulous patients (aged 65 to 75 years) participated in a randomized clinical trial. All patients received a new maxillary complete denture and either a mandibular conventional denture (n = 30) or an implant overdenture on two unsplinted implants (n = 30). Resource-based microcosting of direct and indirect costs (eg, expenses and time cost to patients) of all scheduled and unscheduled visits was conducted through 1 year following delivery of the prostheses. Results: Mean direct costs (1999 CD$) for scheduled visits in the implant and conventional groups were $2,332 and $814, respectively, and mean indirect costs were $1,150 and $810, respectively. Differences between the two groups were significant. Twenty-six patients in each group had unscheduled visits during the study at a median direct cost for the overdentures of $85 and $64 for the conventional dentures. Median indirect costs for unscheduled visits were $163 and $202, respectively. These differences were not significant. Mean total costs of the overdentures were $4,245 and $2,316 for the conventional dentures, and the between-group difference was significant. Conclusion: The direct cost of mandibular two-implant overdenture treatment was 2.4 times higher than that of conventional denture treatment. When indirect costs were added, the implant-to-conventional total cost ratio estimate was 1.8. These cost data can now be combined with estimates of the efficacy of the two types of prosthesis so practitioners and patients can make informed decisions about these prosthodontic treatment concepts.