By means of morphometry, differentiation between the classes of laryngeal squamous cell hyperplasia can easily be performed, mutually (Kleinsasser's classification) and in comparison with normal epithelium. It is rather difficult, however, to distinguish between class II (hyperplasia and atypia) and class III (carcinoma in situ). In the group of class II lesions, two groups of patients could be differentiated: a prognostically favourable and an unfavourable group. When using a linear discriminant analysis, the two groups mentioned could be distinguished morphometrically. In histopathological examination, lesions classified as hyperplasia and atypia (class II), must also be examined with morphometry, because in this way the group at risk can be traced.