SummaryClassical DNAJ proteins are co‐chaperones that together with HSP70s control protein homeostasis. All three classical types of DNAJ proteins (DNAJA, DNAJB and DNAJC types) possess the J‐domain for interaction with HSP70. DNAJA proteins contain, in addition, both the zinc‐finger motif and the C‐terminal domain which are involved in substrate binding, while DNAJB retains only the latter and DNAJC comprises only the J‐domain. There is increasing evidence that some of the activities of DNAJ proteins do not require the J‐domain, highlighting the functional significance of the other two domains. Indeed, the so‐called DNAJ‐like proteins with a degenerate J‐domain have been previously coined as DNAJD proteins, and also proteins containing only a DNAJ‐like zinc‐finger motif appear to be involved in protein homeostasis. Therefore, we propose to extend the classification of DNAJ‐related proteins into three different groups. The DNAJD type comprises proteins with a J‐like domain only, and has 15 members in Arabidopsis thaliana, whereas proteins of the DNAJE (33 Arabidopsis members) and DNAJF (three Arabidopsis members) types contain a DNAJA‐like zinc‐finger domain and DNAJA/B‐like C‐terminal domain, respectively. Here, we provide an overview of the entire repertoire of these proteins in A. thaliana with respect to their physiological function and possible evolutionary origin.