Microquantitative complement-fixation methods have been applied to the detection and quantitation of double-stranded RNA (dsRNA) in cytoplasmic extracts of uninfected and dengue virus-infected primate cell lines. LLC-MK2 and PGLC-33H cells exhibited increased levels of dsRNA following dengue virus infection. Cytoplasmic extracts of infected and uninfected LLC-MK2 cells subjected to density gradient analysis showed that increased levels of dsRNA were associated with structures believed to be virus-specific. Primate cell dsRNA and dengue dsRNA preferentially reacted with rabbit anti-rI_n·rC_n, while reovirus dsRNA and rA_n-containing synthetic duplexes preferentially reacted with anti-rA_n·rU_n.