Eukaryotic 18S ribosomal RNA (rRNA) gene primers that feature a wide coverage are critical in detecting the composition of eukaryotic microscopic organisms in ecosystems. Here, 18S rRNA primers based on consecutive conserved sites and evaluated their coverage efficiency and scope of application to different eukaryotic groups. As PCR is being used increasingly as a diagnostic tool, common conserved regions in eukaryotic 18S rRNA sequences serve as target in PCR assays for better characterization of samples. The Hi-PCR® 18S rRNA SYBr PCR Kit is designed to specifically amplify a region within the 18S rRNA.