Objective: This study was conducted to compare the retention of the mandibular implant-supported overdenture with OT Equator and mini ball and socket attachments. Subjects and Methods: From the removable prosthodontics department clinic, Faculty of Dental Medicine, (Boys, Cairo), Al-Azhar University, 10 completely edentulous patients were randomly chosen. The patients were divided into two groups, group I received two implant-supported overdenture with OT Equator attachment while group II received two implant-supported overdenture with mini ball and socket attachment. The retention was measured using a digital force gauge at the time of attachment connection(T1), after six months(T2), and after twelve months(T3). Statistical analysis was done using SPSS software. the data distribution of normality was done by using the Kolmogorov Smirnov test. Student t-test was used for comparing the means of two groups. Paired t-test was used for comparison between T1, T2, and T3. Results: It was found that group I recorded significantly higher values of retention than group II and there was a gradual loss of retention values in the two groups. Conclusion: OT Equator attachment is more retentive than mini ball attachment.