We compared the efficiency of three methods of agarose and polyacrylamide electrophoresis (using the small tank of the DNA Sequencing System and the large OWL Sequi-Gen Sequencing Cell), for the detection of polymorphism in 21 accessions of orange (Citrus sinensis), using the primer CGA. The polyacrylamide gel gave better resolution of the PCR-amplified RAM products. This method allowed better detection of polymorphic DNA bands, facilitating the identification of genetic variability. The agarose electrophoresis may be more convenient in other applications, due to its low cost and easy implementation. The study of genetic diversity in orange using RAMs separated 51 accessions into seven groups with 0.75 similarity, and 0.25 heterozygosity, revealing low genetic polymorphism. The RAMs technique grouped the accessions into “Common or White”, “Navel” and “Pigmented or “Sanguine”.