Virus disease is one of the most severe diseases of silkworm (Bombyx mon) worldwide. In recent years, a viral disease of silkworm has appeared and caused significant damages to sericulture in Bao Loc (Lam Dong). Typical symptoms of diseased silkworm larvae were stunted growth, body flaccid, dill lethargic soft, vomiting of gut juice and excrete chain type fecus (diarrhea). These symptoms were very similar to those of "flacherie" disease. one of the most important viral diseases of silkworm. Some of viruses causing the flacherie disease are DNA densoviruses (belonging to the family Pavrovirdae). Eight samples of diseased silkworm larvae and two healthy samples collected from Bao Loc (Lam Dong) in 2011 were tested for the presence of densoviruses by PCR using primers specific to these viruses (primers DNV-2 and DNV-3). Testing showed that all diseased silkworm samples were PCR positive while both healthy samples were negative. A 356 nucleotide sequence was obtained from a PCR product. Blast search in GenBank database showed that the detected virus was Bombyx morl densovirus-3 (BmDNV-3). It is the first time this virus was detected and molecularly identified in Vietnam.