The DNA of the nonoccluded baculovirus (Hz-1V) obtained from the IMC-Hz-1 cell line was characterized by physicochemical and restriction endonuclease techniques. Hz-1V DNA isolated from purified virus had buoyant densities of 1.58 and 1.54 g/ml in CsC1-ethidium bromide density gradients, which corresponded to supercoiled and to relaxed circular and linear DNA, respectively. Neutral CsC1 equilbrium centrifugation indicated that the Hz-1V DNA had a buoyant density of 1.7024 g/m1, which corresponded to a guanine-plus-cytosine (G + C) content of 43%. Thermal denaturation indicated a high G t C domain (s) in the Hz-1V genomic DNA. The domain (s), which included about 11% of the total genomic DNA, exhibited a Tms corresponded to G t C contents of 42 and 67%, respectively.