Background: mRNA decay releases, in addition to the regular nucleotides, 7-methyl GMP derived from the 5Ј cap. Results: We describe new members of the 5Ј nucleotidase family degrading 7-methyl GMP to 7-methylguanosine and orthophosphate. Conclusion: Cells have mechanisms to prevent potential salvage of 7-methyl GMP. Significance: 7-Methyl GMP degradation may be important to prevent its incorporation into nucleic acids.