Molecular techniques are crucial for research on nematology, and the processing of samples is essential for their long-term storage prior to analysis. This chapter focuses on DNA extraction, various DNA markers, and polymerase change reaction (PCR). To ensure the preservation of nematodes for extended periods, DESS can be utilized. Moreover, the quality of extracted DNA is vital for proper PCR processing. This chapter offers an overview of nematode isolation and the different techniques for DNA extraction. The utilization of molecular markers presents numerous benefits when studying the genetic makeup of nematode populations. Among these markers, sequence characterized amplified region (SCAR) stands out for its exceptional value in identifying nematodes belonging to the Meloidogyne species. Amplified fragment length polymorphism (AFLP), on the other hand, is a technique that can be employed to analyze the genetic variability of nematodes. It is important to note that these markers are primarily used for plant-parasitic nematodes, which have a significant impact on the economy. This chapter focuses on the most commonly utilized marker for nematodes. After extracting DNA, the next step involves amplifying the target genes through PCR. Various primers, including rDNA and mtDNA, are available for nematode genes and serve useful taxonomic purposes. However, precise primer design is critical for achieving accurate nematode diagnosis. Both DNA and primers must be of high quality to ensure successful PCR. Eco-friendly standard dyes like SafeView can be employed to visualize PCR products. This chapter offers a comprehensive guide to PCR processing and DNA visualization techniques.