Parkinson's disease is caused by the premature death of neurons in the midbrain. By contrast, cancer spawns from cells that refuse to die. We would therefore expect their pathogenic mechanisms to be very different. However, recent genetic studies and emerging functional work show that strikingly similar and overlapping pathways are involved in both diseases. We consider these areas of convergence and discuss how insights from one disease can inform us about, and possibly help us to treat, the other.