In June 2005 an International Congress on Plant Mitochondrial Biology was held in Obernai, France with about 200 participants where rapid progress was evident in a number of areas. Based on the lectures we invited a number of colleagues to write reviews on exciting and emerging fields of study and you will find 12 of them in this issue. We also invited all the participants at that meeting to submit primary articles and a gratifying number responded. The result is that 12 primary articles are also included in this issue. Together these articles paint a vivid picture of a classical research field in rapid progress as outlined below.