Several human diseases are associated with the presence of toxic fibrillar protein deposits. These diseases called protein misfolding disorders, are characterized by the accumulation of misfolded protein aggregates in diverse tissues. Strong evidence indicates that the conversion of a normal soluble protein into a beta-sheet-rich oligomeric structure and further fibrillar aggregation are the key events in the disease pathogenesis. Therefore, a promising therapeutic target consists of the prevention and dissolution of misfolded protein aggregates. Peptides designed to specifically bind to the pathogenic protein and block and/or reverse its abnormal conformational change constitute a new class of drugs. This article reviews this approach, describing diverse compounds reported to have this activity.