Carnation yellow fleck virus (CYFV) was partially purified from spray carnations, Dianthus caryophyllus, by clarification with bentonite, concentration with 4% polyethylene glycol, and further purification by rate zonal and isopyonic gradient centrifugation. These methods enabled almost complete removal of carnation mottle virus (CarMV) particles present in the plant material. The purified particles had an unusual ultraviolet absorption spectrum (A_260/280 = 1.53), contained about 5% RNA (estimated from a buoyant density p = 1.325 in CsCl), with an extinction coefficient of E 0.1%₂₆₀=2.27. The molecular weight of the coat protein subunit was about 23,500. In the serological ring precipitin test, CYFV antiserum had a titer of 1/256 and 1/8 against dissociated virus (CYFV-D) in the gel diffusion tests. The antisera did not react with extracts from healthy plants nor with those from plants infected with CarMV, carnation etched ring, and carnation vein mottle viruses.