RAS mutations are found in about 25% of acute myeloid leukemia (AML) cases. The importance of these changes is unknown. If RAS mutations confer growth advantage to leukemia subclones in which they emerge, substantially more nonconservative than conservative mutations should be found. The incidence of conservative mutations was not reported previously. We sequenced N-RAS and K-RAS codons 12 and 13 and N-RAS codon 61 in 20 subjects with newly diagnosed AML. Four nonconservative N-RAS mutations and 4 conservative K-RAS mutations were found. There were no differences between subjects with AML and nonconservative RAS mutations and those with conservative or without RAS mutations. Additional studies are needed to examine the incidence of conservative RAS mutations in subjects with AML.