An important question facing most of the clinicians is whether the bone replacements graft help in preserving bone in the post extraction period, and whether they limit or reduce the alveolar bone height shrinkage. The aim of this study was to assess the effectiveness of xenografts (OsteoBiol® Gen-Os) in ridge height preservation using cone beam computerized tomography (CBCT). .Materials and methods: This study out was carried as a randomized controlled clinical trial Thirty patients requiring extraction of mandibular first molars were enrolled in this study, they are randomly divided into two equal groups, and each consisted of fifteen participants. Group I (study Group): received (OsteoBiol® Gen-Os; Tecnoss srl, Giaveno, Italy) and collaplug following the tooth extraction, while group II (control Group), received (Bio-oss® Geistlich Pharma AG, Switzerland) and collaplug serving as a control group. Vertical ridge changes were studied in the two groups from the time of extraction to four and nine months after the extraction using CBCT. Results: The mean loss of vertical bone was 0.66 mm ±0.071 and 0.567±0.080 in Groups I and II respectively at 4 months follow up interval, whereas, it was 0.397±0.057 for the study group and 0.375±0.055 for the control group at 9 months postoperatively . A non-statistically significant difference was found between the test and control groups. Conclusion: The use of Osteobiol Gen Os® is effective in ridge preservation. It decreased the loss of alveolar bone vertically following extraction.