Inclusion Criteria:  Patients who underwent either PRP or mesotherapy at our dermatology clinic during 1/1/2011 and 30/12/2020 Male patients with a clinical/ trichoscopic/ histologic diagnosis of androgenetic alopecia (stage II to V according to the Hamilton-Norwood Scale) Female patients with a clinical/ trichoscopic/ histologic diagnosis of androgenetic alopecia (stage I to III according to Ludwig Classification) Patients receiving no treatment or being treated for more than six months for androgenetic alopecia without change in medication. Examples of medications and interventions include, oral/topical finasteride, oral/topical minoxidil, antiandrogens, hormonal substitution, hormonal contraceptives, phototherapy/laser, cryotherapy, microneedling. Patients who underwent trichoscopic examination and phototrichographic evaluation with our digital dermatoscope, before treatment, a month after the last injection and 3 months after treatment. Trichoscopic photos are required to be taken from the midfrontal area and from the vertex -defined as the intersection of the line through the midsagittal line and the line passing through the external auditory canals in the coronal plane.  Exclusion Criteria:  Patients with other types of alopecia, other than androgenetic alopecia Patients with two or more diagnoses of hair loss , for example androgenetic alopecia and telogen effluvium or alopecia areata. Patients who started concomitant medication for hair loss within six months of treatment with PRP or mesotherapy. Medications and interventions include, oral/topical finasteride, oral/topical minoxidil, antiandrogens, hormonal substitution, hormonal contraceptives, phototherapy/laser, cryotherapy, microneedling. Hair transplantation to the vertex /midfrontal area Patients with no trichoscopic examination/ phototrichographic evaluation Patients lost to follow-up / withdrew from treatment