Thioredoxins are small proteins catalyzing thiol-disulfide interchange and are involved in the regulation of the redox environment of the cell. In plants, the thioredoxin system is particularly complex since at least 20 thioredoxin isoforms are found in the plant model Arabidopsis thaliana. Based upon primary sequence analysis and subcellular localization, thioredoxins can be classified into different groups and subgroups. Different pathways allowing thioredoxin reduction also coexist in the plant involving ferredoxin-thioredoxin reductase, thioredoxin reductases and the glutathione/glutaredoxin system. This review discusses the literature of plant thioredoxins with emphasis on recent findings in the field.