1. The use of the Metals Research Macrotome for cutting 100 μ thick sections of fresh, unfixed specimens of arthritic human femoral heads and normal goat condyles is described.

2. A technique for isolating living cells from these slices by decalcification followed by enzymic digestion is reported.

3. The microscopic appearances of the fresh slices, the decalcified slices and the isolated cells as seen by incident or transmitted fluorescent lighting, by phase-contrast microscopy, by scanning electron microscopy and by histological and cytological techniques are illustrated.

4. These techniques might be applicable to the examination of biopsy specimens of pathological bone or to basic research on bone cells.

1. Methods for culturing cells isolated from slices of arthritic human or normal mammalian cancellous bone are described.

2. The capacity of the cultured cells to take up and hydroxylate labelled proline has been investigated.

3. Sections of the partially decalcified bone and of the isolated cells have been examined by transmission electron microscopy.

4. The possible significance of the results and observations are discussed. We are deeply grateful to Dame Janet Vaughan, who very kindly read this manuscript and made several valuable suggestions and criticisms. We are much obliged to Dr Sylvia Fitton-Jackson for her advice on the techniques of tissue culture and for giving us the composition of her chemically defined medium. Dr Palfrey kindly allowed one of us, M. J. Dickens, to learn transmission electron microscopy in his department at St Thomas's Hospital Medical School under the expert tuition of Mr G. Maxwell. Mr R. Hockhan and Mr M. Hepburn of the University of Surrey Structural Studies Unit helpfully instructed in the operation of the transmission electron microscope. Our special thanks are due to Mr E. P. Morris for his competent and enthusiastic technical assistance.