Circumstantial evidence demonstrating a role for circadian rhythms in cancer has been presented but there is little direct molecular evidence to support this idea in human cancer. Herein, we report a significant similarity between fly genes with strong circadian rhythms and human genes under expressed in pancreatic cancer. The list of genes includes both circadian regulator genes, such as period 1 and DEC1, and downstream effectors, such as ubiquitin specific protease 30. This observation may indicate that the pancreas peripheral clock is disrupted in pancreatic cancer and are consistent with the recent proposals that circadian genes act as tumor suppressors.