Protein aggregates are formed in cells with profoundly perturbed proteostasis, where the generation of misfolded proteins exceeds the cellular refolding and degradative capacity. They are a hallmark of protein conformational disorders and aged and/or environmentally stressed cells. Protein aggregation is a reversible process in vivo, which counteracts proteotoxicities derived from aggregate persistence, but the chaperone machineries involved in protein disaggregation in Metazoa were uncovered only recently. Here we highlight recent advances in the mechanistic understanding of the major protein disaggregation machinery mediated by the Hsp70 chaperone system and discuss emerging alternative disaggregation activities in multicellular organisms.