We previously reported a simple subtyping method, restriction site-specific PCR (RSS-PCR), for dengue virus serotypes 2 and 3; here we describe its application for subtyping dengue virus serotypes 1 and 4. Three major RSS-PCR types were observed for dengue virus serotype 1 and two types were observed for dengue virus serotype 4, in agreement with previous strain classifications based on sequence analysis. Because of its simplicity, this method is amenable to rapid subtyping and application to epidemiological studies of dengue in countries where dengue is endemic.