The article offers a critical review of the diagnosis of focal diseases of the vertebral column, based on 200 histological vertebral column examinations. The findings obtained by means of the roentgenological, histological and bacteriological examinations can be subdivided into 6 groups: 1. Non-specific and specific cases of spondylitis (59 patients); 2. Systemic malignant diseases and primarily malignant tumours (23 patients); 3. Metastases (71 patients); 4. Benign tumours (11 patients); 5. Miscellaneous cases (28 patients) and 6. Unclarified cases (8 patients). The authors comment on the following points with specific reference to the results obtained by them: a) Possibilities and limitations of roentgenological diagnosis: roentgenologically, the inflammatory diseases are most easy to identify, but is not always possible to differentiate safely between non-specific, specific and plasmacellular spondylitis. There are clear limitations to the diagnosis of the type of focal diseases of the spinal column; this applies particularly to the benign and malignant types of tumours. b) Necessity of arriving at an accurate diagnosis: it is imperative to aim at an accurate diagnosis before any meaningful therapy can be initiated. The mandatory need for this is explained via examples covered by the present study. c) Closed or open biopsy: it is shown by means of a review of the literature that open biopsy yields more representative material for the histological examination than closed needle biopsy. It goes without saying that this is a true prerequisite for an accurate histological diagnosis. In this connection, the authors go into the details of the difficulties governing any histological examination. d) informative value of further additional examinations: Scintigraphy, tomography and computer tomography may be valuable aids in the discovery and better visualisation of a vertebral focus, but they are not helpful in arriving at a diagnosis regarding the type of focus involved. Laboratory examinations are not very helpful, either. e) Accuracy of the authors' own diagnostic measures: in spite of open biopsy, 177 cases only out of 200 (88%) could be diagnosed on a purely histological basis. In 12 further cases, diagnosis was established after correlation of the histological finding with the x-ray film. 8 cases (4%) could not be clarified. In 7 patients (3.5%) it must be assumed that the focus was not located despite open biopsy.