This 6-month clinical study evaluated the use of a porous bone mineral matrix xenograft (Bio-Oss) as an adjunct to a biodegradable barrier membrane (Bio-Gide) to support healing following the immediate placement of transmucosal implants into extraction sockets. Twenty adult patients scheduled for tooth replacement with dental implants were accepted for participation. Following implant placement into the extraction site, subjects were assigned to one of two treatment alternatives for the remaining bone defect around the implant: (1) Bio-Oss + Bio-Gide membrane (test); or (2) Bio-Gide membrane (control). The treatment outcome was evaluated after 6 months by the use of clinical and radiographic variables. The null hypothesis of no treatment group differences was tested by ANOVA. At 6 months, the radiographic bone level remained unchanged compared to baseline in the test and control groups. No differences were observed between test and control groups in terms of mean probing attachment level. At proximal sites, the soft tissue margin was located 2.6 mm more coronal than the shoulder of the implant in the test group, compared to 1.3 mm in the control group. The corresponding figures for the lingual aspect were 2.3 mm and 1.1 mm, respectively, and at buccal sites 2.1 mm and 0.9 mm, respectively. The use of deproteinized bovine bone mineral as a membrane support at immediately placed transmucosal implants may offer an advantage in areas with high esthetic demands in terms of soft tissue support.