The present invention relates to bis-heteroaryl compounds of formula (I), pharmaceutical compositions containing them, and methods of using them, including methods for preventing, reversing, slowing, or inhibiting protein aggregation, and methods of treating diseases that are associated with protein aggregation, including neurodegenerative diseases such as Parkinson's disease, Alzheimer's disease, Lewy body disease, Parkinson's disease with dementia, fronto-temporal dementia, Huntington's Disease, amyotrophic lateral sclerosis, and multiple system atrophy, and cancer including melanoma.