Genetic studies indicate that protein homeostasis is a major contributor to metazoan longevity(1). Collapse of protein homeostasis results in protein misfolding cascades and the accumulation of insoluble protein fibrils and aggregates, such as amyloids(2). A group of small molecules, traditionally used in histopathology to stain amyloid in tissues, bind protein fibrils and slow aggregationin vitro and in cell culture(3,4). We proposed that treating animals with such compounds would promote protein homeostasis in vivo and increase longevity. Here we show that exposure of adult Caenorhabditis elegans to the amyloid-binding dye Thioflavin T (ThT) resulted in a profoundly extended lifespan and slowed ageing. ThT also suppressed pathological features of mutant metastable proteins and human beta-amyloid-associated toxicity. These beneficial effects of ThT depend on the protein homeostasis network regulator heat shock factor 1 (HSF-1), the stress resistance and longevity transcription factor SKN-1, molecular chaperones, autophagy and proteosomal functions. Our results demonstrate that pharmacological maintenance of the protein homeostatic network has a profound impact on ageing rates, prompting the development of novel therapeutic interventions against ageing and age-related diseases.