Purpose To assess the potential of platelet‐rich plasma (PRP) subcutaneous injection of to treat alopecia and to evaluate local toxicity.

Materials‐Methods Twelve Hairless rats were used. At D0, we performed systematic clinical examination and divided the rat back into four quadrants (Q). We initiated subcutaneous injection using either PRP in PRPQ+, platelet‐poor plasma (PPP) in PPPQ+, physiological serum (PS) in PSQ+, or no treatment (Q4). At D7, D14, D21, and D28 but also second month (M2), M3, M4, M5, rats had exactly the same injection procedure. Follow‐up with PRP efficacy and toxicity at D28 and M6 using clinical and histological evaluation was performed.

Results Hair density was significantly improved at D28 and at M6 for PRPQ+ vs PSQ+ (respectively, P = .0156 and P = .0313), PPPQ+ (respectively, P = .042 and P = .046). Significant histological improvement was observed between D28 and M6, for PRPQ+ vs PPPQ+ and PSQ+ for vessels (respectively, P = .0160 and P = .021), collagen (respectively, P = .0036 and P = .032), and epithelium (respectively, P = .0138 and P = .022) with no local toxicity.