The single-stranded DNA (ssDNA) of bean golden mosaic virus (BGMV) was resolved into two components by polyacrylamide gel (2.5%) electrophoresis in 8 M urea and by rate-zonal sedimentation in 5-20% alkaline sucrose density gradients. Viral DNA, either unfractionated or fractionated and electroeluted from polyacrylamide gels, was spread for electron microscopic examination. Unfractionated DNA and the slower of the two fractionated components contained predominantly circular molecules. The faster component consisted entirely of linear molecules. Circular molecules had contour lengths corresponding to 8.0 x 10(5) daltons.