BACKGROUND Striae distensae (SD) are dermal scars associated with atrophy of the epidermis. OBJECTIVE To evaluate the effect and safety of intralesional injection of platelet-rich plasma (PRP) versus topical tretinoin 0.05% in treatment of SD. METHODS Thirty patients (27 females and 3 males) had bilateral striae distensae were enrolled in this study. In every patient, half of the selected striae were treated with PRP intralesional injection. The other half was treated by topical tretinoin. Skin biopsies were taken from both sides before and after the treatment. Digital photographs were taken at the baseline and at the end of follow-up period. Clinical improvement was evaluated by 2 blind dermatologists in addition to the patient’s satisfaction rating. RESULTS There was statistically significant improvement in the SD treated with PRP and topical tretinoin cream. The improvement was more in the SD treated with PRP injections (p = .015). Patient’s satisfaction showed that the improvement was more in the PRP-treated side (p = .003). Collagen and elastic fibers in the dermis were increased in all biopsies after treatment. CONCLUSION PRP injection and topical tretinoin are safe for the treatment of SD, but PRP is more effective and it gives better therapeutic response than tretinoin.