Alfred Blaschko (4 March 1858 – 26 March 1922) was a German dermatologist who was a native of Freienwalde an die Oder. In 1881 he earned his medical doctorate at Berlin, and afterwards worked with Georg Wegner (1843-1917) in Stettin. Later he opened a private dermatological practice in Berlin.
Blaschko specialized in the study of occupational dermatoses and prophylaxis of venereal disease. He performed studies of prostitution and examined the sanitary conditions in this profession. In 1902 with Albert Neisser he co-founded the Liga zur Bekämpfung der Geschlechtskrankheiten (German Society for the Fight Against Venereal Diseases) in Berlin.
In 1901 at the Seventh Congress of the German Dermatological Society held in Breslau, Blaschko presented his observations concerning a rare dermatological condition. It involved patterned skin lesions that were linear on the extremities, S-shaped on the anterior trunk, and V-shaped on the back. Blaschko had based his findings on examinations of over 140 patients with nevoid and acquired linear skin diseases, which he then transposed the pattern of each patient onto dolls and statues. This unusual patterned condition was later referred to as lines of Blaschko. The embryological basis regarding the distribution pattern of the lines of Blaschko is considered a mystery, however they are thought to trace pathways of ectodermal cell development.