The standard methods used to diagnose scalp psoriasis vary in sensitivity, reproducibility, and invasiveness. Videodermoscopy can be used to explore microcirculatory modifications in skin diseases. Psoriasis presents three pathognomonic vascular patterns: red dots, hairpin vessels and red globular rings. Our aim was to create a videodermoscopy scalp psoriasis severity index (VSCAPSI) for evaluation of scalp psoriasis, especially mild and moderate forms that often are not clinically appreciable. VSCAPSI takes into account the area of the scalp affected by psoriasis, the presence and morphology of vascular patterns, the erythema and desquamation. Videodermoscopy images obtained between November 2009 to June 2010 from 900 participants with various scalp and hair disorders were reviewed for distinguishing features. During the 2010 Italian congress on psoriasis, in order to assess the reproducibility and efficacy of the VSCAPSI, 146 dermatologists were asked to evaluate 16 videodermoscopy images of scalp psoriasis using the VSCAPSI. Of the 900 patients, 85 new cases of scalp psoriasis were diagnosed. The other 815 patients were found to be suffering from different scalp and hair diseases. Of 146 dermatologists, 28 did not recognize erythema, 15 desquamation and 7 the vascular patterns. The VSCAPSI provides important evidence for early diagnosis, differential diagnosis, for follow-up and screening.