OBJECTIVE Retention and resistance of the implant-tissue supported overdenture may be affected by the type of attachment. The aim of this research was to compare the retention and resistance of Nobel Biocare Ball (NBB), Nobel Biocare Bar and Clip (NBBC) and Sterngold ERA Red (ERAR) attachments on an implant-tissue supported overdenture model. METHODS The attachment samples were divided into 3 groups of NBB, NBBC, and ERAR (5 samples in each group). Two parallel Nobel Biocare Branemark implants were placed symmetrically at the symphysis region of a mandibular test model. A metallic overdenture was fabricated precisely adapted to the model and attached to a Zwick testing machine (crosshead speed of 51 mm/min). Dislodging tensile forces were applied in three vertical, oblique, anterior-posterior directions and two situations, at the beginning and after 100 times of insertion/removal of the overdenture, for each sample. The maximum dislodging force was measured. A One-way ANOVA test was employed followed by Tukey's test. RESULTS ERAR was the most retentive and resistant in both situations. NBB and NBBC showed the same anterior-posterior resistance at the beginning. All test groups represented a large amount of retention and resistance loss after the insertion/removal of the overdenture, while NBBC showed a higher loss of anterior-posterior resistance than NB. CONCLUSIONS A highest level of retention and resistance was seen in ERAR. The retention and resistance were affected by the wear of attachments.