If one wishes to have a stock of high molecular weight viral DNA that can be stored for long periods of time with minimal shearing or degradation, the viruses can be embedded in agarose before extraction. Extraction of embedded cells is the standard procedure for sizing the genomes of bacteria and\u00a0yeast by PFGE (Sambrook and Russell 2001), and a similar protocol can be used for embedded viruses (Rohozinski et al. 1989; Lanka et al. 1993; Wommack et al. 1999; Sandaa et al. 2010, this volume).This is a protocol from:\u00a0Steward, G. F. and A. I. Culley. 2010. Chapter 16: Extraction and purification of nucleic acids from viruses.\u00a0Manual of Aquatic Viral Ecology. Waco, TX:American Society of Limnology and Oceanography. doi:10.4319\/mave.2010.978-0-9845591-0-7Please see the published manuscript for additional information.