Purpose The current study was conducted to evaluate the effect of fascia lata allograft (FLA) versus subepithelial connective tissue grafts (SCTGs) in increasing the peri-implant mucosal thickness when placed simultaneously with dental implant histologically and histomorphometrically in human. Patients and methods A total of 16 patients who met the inclusion criteria were selected to be included in this study. They were randomly classified into two treatment groups: a test group (FLA) and a control group (SCTGs), with eight implantation sites in each group. Three months after implantation, the augmented sites were located, soft tissue biopsies (n = 16) (punch biopsy) were collected for histological and histomorphometry analysis. Results Both grafts were integrated well into the surrounding soft tissues. Regarding percentage of fibrovascular tissue at 3 months postsurgery showed a significant increase in FLA graft in comparison with SCTGs it was (36.52 in the FLA group and 24.17 in the SCTGs group). A significant difference in the vimentin expression percentage in favor of FLA grafts in comparison with SCTGs; it was (24.95% for FLA) where it was (7.24% for SCTGs). Conclusions FLA was found to be clinically save with no adverse reactions and integrated well into the surrounding soft tissues and organized by newly formed connective tissue, and provided results are comparable to SCTGs (the gold standard).