TRIzol is a monophasic solution of phenol and guanidine isothiocyanate used for the extraction of RNA, DNA and proteins from tissues or cells. However, few studies have described its application to DNA extraction due to its time-consuming procedure. We present a TRIzol-modified method of extracting DNA from tissues using the TRIzol reagent and a silica column, which requires only one-third of the time required for the classic extraction procedure. Spectrophotometric analysis showed that the 260/280 and 260/230 nm optical density ratio of the DNA extracted using the TRIzol-modified method is ideal and equal to that obtained by the classic method and commercial DNAiso methods. The DNA extracted by the TRIzol-modified method had the same performance in a restriction enzyme digestion and quantitative PCR as that extracted using the classic method. Using the TRIzol-modified method saves time, simplifies the DNA extraction procedure, and facilitates various molecular biology assays.