Purpose:This in vitro study was aimed to compare retention force of maxillary implant retained palatelessoverdenture with two and four Equators versus Locators V shaped palatal vault model. Materials and Methods:The in vitro study analysis will be established as follows:Standard prefabricated two dimensional  maxillary acrylic resin models.For this model the following will be done:  Placement of two implants with locator attachment placed on canine region will be done and  Placement of another two implants on second premolar region of the same model will be done and Placement of two implants with two  equators attachment placed on canine region will be done and Placement of another two implants with equator attachment placedon second premolar region will be done.- Measurement of retention by universal testing machine will be done. Results:It was found that Locator attachments with four implants- retained palatelessoverdenture recorded the highest retention force mean values X ± SD was (91.86±6.04N) followed by Locator attachments with two implants- retained palatelessoverdenture X ± SD (79.73±4.87 N) then Equator attachments with four implants- retained palatelessoverdenture X ± SD (77.77±6.25N) while Equator attachments with two implants- retained palatelessoverdenture recorded the lowest retention force mean values X ± SD (52.58±3.87 N). One way analysis of variance ANOVA tests showed there was that the difference between groups was statistically significant (P=<0.0001). Tukey's post-hoc test showed non-significant (p>0.05) difference between locator with two implant and equator with four implants . Conclusions:Within the limitations of this in vitro study it can be concluded that both attachment system i.e Locator® and OT equator showed a reduction in retention after cyclic fatigue period. Locator® attachment system used with pink nylon inserts showed superior retentive properties when compared to OT equator clear pink inserts. The cost of maintenance is also a factor to be considered when selecting the implant overdenture attachment system, OT equator attachments system is considered more cost-effective option in relation to the cost of replacing the Locator® nylon inserts. Recommendation: Further research is needed to evaluate the retentive properties of these components for longer periods of cyclic fatigue. Also further research is recommended to test the retention properties of the other nylon inserts and retention with different implant angulations.