The endoplasmic reticulum is equipped with a quality control function that retains misfolded and unassembled proteins and allows only structurally mature polypeptides to be transported to their final destination. The retained proteins are eventually retro-translocated to the cytosol and destroyed by a process called endoplasmic reticulum-associated degradation (ERAD). Besides being involved in the degradation of aberrant polypeptides, the ERAD pathway is used to regulate cellular functions and is exploited by some plant and bacterial toxins to reach the cytosol after internalization by target cells. After summarizing the general characteristics of the ERAD pathway, we describe the features of known plant ERAD substrates and of the plant degradative machinery, highlighting the role of protein disposal in the response to endoplasmic reticulum stress.