The present study was designed to compare two stud attachment systems [Locator and Ball / O-Ring attachment] in mandibular overdenture cases retained by two implants in the inter-foraminal area. Twenty completely edentulous male patients received mandibular overdentures retained by two implants were randomly assigned into two groups; Group-I received Locator attachment while Group-II received Ball / O-Ring attachment. A comparison based on implant stability quotient [ISQ] was done using Resonance Frequency Analyzer [Osstell, ISQ] and another comparison was conducted based on the marginal bone loss using cone beam computed tomography [CBCT]. The patients were then scheduled for recall appointments up to two years follow up period starting from the loading time. The statistical analysis of the results reported no significant difference for the marginal bone loss & ISQ values between the two groups at all intervals except the third month implant stability results which showed a significant difference between the two groups with better stability results in the Locator attachment group (at p<0.05). Within the limits of the present study, it may be concluded that both studied attachment systems are successful and useful however the Locator attachment system shows superior initial stability results than the Ball attachments.