Erythrocytosis is defined by an increased number of red blood cells and at the same time elevated levels of hematocrit and hemoglobin. The cause of primary family erythrocytosis (FE) type 1 (ECYT1) is the mutation in the erythropoietin receptor gene (EPOR). A diagnostic investigation has not yet been established in Slovenia, which would cover the testing of the EPOR gene in relation to the occurrence of this disease. We retrieved 24 polymorphisms of the EPOR gene associated with FE using systematic review of the literature; all of them located in exon 8. Using SIFT and PolyPhen tools we determined 33 missense variants with the highest predicted effect on protein function, which included ten variants previously associated with erythrocytosis. We optimized the PCR reaction for amplification of the exon 8 of the EPOR gene. The nucleotide sequence of the EPOR gene was analyzed and compared among two patients with idiopathic erythrocytosis, two healthy controls and the reference genome. We did not detect any nucleotide sequence differences, thereby excluding suspicion of ECYT1 in patients. We were able to transfer the new diagnostic method for the detection of FE in clinical use to the Specialized Hematology Laboratory of the Clinical Department of Hematology at the University Clinical Center Ljubljana.