The purpose of this randomized, controlled, split-mouth study was to compare the behavior of the extracellular matrix membrane (EMM) with autogenous subepithelial connective tissue graft (SCTG) when used as a biologic barrier in the covering of immediate implant placement after modified edentulous ridge expansion. A total of five patients between 40 and 59 years of age (three men, two women) were selected for this study and randomly assigned to one of two groups: EMM (test) or SCTG (control). Treatments were randomly assigned at the same surgical appointment. A total of 29 screw-shaped titanium implants were inserted. Clinical examinations and prophylaxis were performed in recall sessions at 2, 4, and 16 weeks postsurgery. A soft tissue biopsy was performed at both sides 4 months postsurgery. This study indicates that both procedures were effective and predictable in barrier membrane coverage after bone expansion and immediate implant placement. The use of EMM may be a valid alternative to SCTG as a biologic barrier in bone expansion procedures. The use of EMM eliminates the need for the palatal donor site and, as such, provides a less invasive solution.