Invertebrate models of several human neurodegenerative diseases have recently been described. These models faithfully replicate key neuropathological features of the human disorders. Because the basic cell biology of the nervous system is very similar in vertebrates and invertebrates, the sophisticated and rapid genetic analysis feasible in Drosophila and C. elegans promises significant insight into human neurodegenerative syndromes. In addition, the short lifespan, small size, and ease of culturing make worms and flies ideal for drug testing.