Abstract Acute myeloid leukemia (AML) is a malignant hematopoietic disease with poor clinical course and outcome. There is a constant need for new prognostic factors that could facilitate patient's risk stratification. The aim of our research was to determine the phosphorylation levels of PI3K/Akt and MAPK pathways in leukemic cells, their relation to P-glycoprotein expression/activity, and their prognostic significance in adult de novo AML. A total of 118 AML patients were enrolled in the study. In a multivariate Cox regression analysis we found P-gp activity and Akt phosphorylation were independent poor prognostic factors of OS. In contrast, phosphorylated ERK1/2 represents a favorable prognostic factor of OS and RFS. A negative correlation between P-gp activity and p38 phosphorylation level was found, implying a possible role of this MAPK pathway in P-gp regulation. In addition, we found correlation between Akt and p38 phosphorylation levels indicative of two signaling cascades co-activation in AML.