Background: DNA of high quality and large quantity obtained from buccal cells is important for accurate analysis. The present study is conducted to examine quality and purity of DNA extracted by three commonly used methods and to determine the infl uence of process time on PCR amplifi cation. Materials and methods: The DNA concentration was determined at 260 nm by a spectrophotometer. The ratio of 260/280 was measured to evaluate DNA purity. The collected buccal samples were subjected to DNA extraction immediately or after storage at 4oC for 3 days. The adequacy of the buccal DNA extracts for PCR-based assays was assessed by amplifying three fragments of the specifi c gene in different sizes (1300 bp, 581 bp, and 300 bp). Results: The mean DNA concentration at 260 nm was found to be 1.5, 1.4, and1.1 μg/ml for phenol-chloroform, QIAamp kit, and NaOH methods, respectively. The DNA purity were 2.1, 2.0, and 2.4 for
phenol-chloroform, QIAamp kit, and NaOH methods, respectively. The NaOH method yielded the lowest concentration and purity of DNA when compared individually with the other two methods, while there was no statistical difference between the phenol-chloroform and the QIAamp kit methods. Different band patterns were observed in the agarose depending on whether the samples were processed immediately or with delay. Some degree of degradation in the DNA band was noted when there was delay in sample processing. However, whether processed immediately or with delay, the samples can successfully amplify PCR products up to 1300 bps. Conclusion: Our results indicated that buccal cell DNA samples can provide precise estimates of human amplifi able DNA. The DNA isolated from buccal cells under appropriate storage can be successfully used in PCR-based assays.