It has been a great pleasure to be involved in the writing of the sixth edition of Wheater’s Functional Histology. For the new edition, we have again kept the layout that has proved popular and successful in the past. Short bursts of introductory text are followed by a wealth of illustration, light micrographs, electron micrographs and line drawings, designed to elucidate the key points of histology without drowning the student in unnecessary detail. This text and atlas is designed to be accessible to the absolute beginner and, with that in mind, we have provided appendices at the back outlining the basics of microscopy and histological staining techniques, as well as a basic glossary. In addition to updating the text where required, we have extensively improved and added to the micrographs. Many of the students using this text and atlas will be involved in medicine and, accordingly, we have increased the clinical correlations in this edition, in the hope of making apparently arcane histological details easier to remember. We have also added a brief review section at the end of each chapter, useful for that last minute examination preparation! It was a great loss to the authorship team that James Lowe, Alan Stevens, John Heath and Phil Deakin decided, for various reasons, not to take part in the production of this new edition. We wish them good luck in their new endeavours and assure them that their input has been very much missed. The resulting gap has been filled by Geraldine O’Dowd and Phillip Woodford, who have laboured mightily to bring forth this book. Geraldine is the first author on the team who had used an earlier edition of this work during her own student days and she brings along the memory of her own perspective as an undergraduate, helping us to augment those features which help, as well as aiming to eliminate any sources of confusion or unnecessary complexity. We hope that students in all areas of science and medicine will find this revised and updated edition useful in their studies.