Professor Kark has made a great contribution to the study of renal disease by developing a really reliable and safe method of renal biopsy which has been widely adopted. This new technique is already paying dividends in many hands; our knowledge of the natural history of renal disease and of histological changes, particularly when evaluated with both light and electron microscopy, has developed rapidly as a result of it. This volume contains the study of lupus nephritis previously published by Professor Kark's team in Medicine in March I957. It is, in fact, a bound reprint, with the original figures and 307 references. There is, of course, the usual table of contents, but no index. This is a most careful and well-documented study of the author's cases, giving full details of the clinical features and course, the pathological findings and the histological changes revealed mainly by biopsy. Many of the sections are reproduced in colour. The authors have produced a beautiful monograph and their findings are of the greatest interest and importance. Their discussion of the relationship of S.L.E. and lupus nephritis to other diseases, in which they collect together many important earlier observations, occupies I8 pages and will be particularly valuable to those interested in other fields. Very often, as in their discussion of the relationship of S.L.E. to rheumatoid arthritis (a problem often confronting the general physician), the authors are able to add an account of a carefully studied case of their own to illustrate it. They have certainly been fortunate in collecting such magnificent material to study. Of their 33 cases, 22 were studied more than once during steroid therapy; unfortunately, though we are told that steroids did not influence the histological changes, nothing is said of their effect on the prognosis. This volume is, of course, as beautifully produced as the parent journal. What a pity that the junior author's name is misspelt on the title page. MEDICAL LABORATORY INVESTIGATIONS: THEIR USE AND INTERPRETATION