The radial forearm free flap is frequently chosen for phalloplasty; however, flap size required for phalloplasty is associated with a large scar burden and functional concerns. We sought to investigate donor site functionality, aesthetics, and volume deficits in a cohort of individuals who underwent radial forearm phalloplasty (RFP) with donor site skin grafting alone or dermal substitute and subsequent skin grafting. Donor site functionality was assessed using the quick Disabilities of Arm, Shoulder, and Hand (qDASH). Patient- and clinician-reported aesthetics were assessed using the Patient and Observer Scar Assessment Scale (POSAS). An Artec Leo three-dimensional scanner was used to measure volumetric differences from the donor site forearm and contralateral forearm. Fifteen patients who underwent RFP agreed to participate. No statistically significant differences were identified between different donor site closure methods regarding qDASH, patient-reported POSAS, or total volumetric deficits. A blinded clinician reported that POSAS approached significance at 4.7 for biodegradable temporizing matrix (BTM), 4.2 for Integra, and 3.0 for split-thickness skin graft (P = 0.05). No statistically significant differences were identified regarding distal, middle, or proximal volume deficits; however, a trend was observed regarding total volumetric deficits with BTM experiencing the lowest deficit (10.3 cm3) and skin graft experiencing the highest deficit (21.5 cm3, P = 0.82). The addition of dermal matrix (BTM or Integra) to the treatment algorithm for RFP did not show statistically significant improvement in donor site volume deficits, patient-reported scar appearance (POSAS), or functionality (qDASH).