A cutting-edge and controversial attribution of a drawing known as La Bella Principessa, to Leonardo da Vinci, reported in the press worldwide, makes an interesting case of contemporary connoisseurship. Unfortunately, only studies in favour of the attribution have been published so far in the form of books (M. Kemp and P. Cotte; A. Vezzosi; P. Silverman), articles (C. Geddo, M. Gregori, D. R. E. ... [Show full abstract] Wright) and web material (Lumiere Technology). Nevertheless, the attribution has not been unanimously accepted. The purpose of this paper is to systematically examine all the arguments against the attribution, as well as making comparisons with indisputable works by Leonardo, which have so far been lacking. A careful and detailed analysis of all the evidence available discloses a number of significant problems and contradictions, which undermine the attribution. The paper will show that neither the identification of the sitter as Bianca Giovanna Sforza, put forward by Kemp, nor the theory of the Sforziad manuscript in Warsaw, proposed by Wright, have any solid foundations. The paper also discusses the Marchig provenance, the style and technique of the drawing, the problem with the dating, and demonstrates why all these factors cast doubts on this attribution. A number of works by Leonardo da Vinci and de Predis, as well as a sculpted bust by Cristoforo Romano, are suggested as possible sources for the drawing.