The absorption, distribution and elimination of 14 C-labelled flumequine were studied using whole body autoradiography and liquid scintillation counting. Flumequine was administered to eel Anguilla anguilla, turbot Scophthalmus maximus and halibut Hippoglossus hippoglossus intravenously and orally as a single dose of 5 mg kg . The turbot and halibut studies were performed in salt water (salinity of 32 ‰) at temperatures of 16 ± 1°C (turbot) and 9.5 ± 0.5°C (halibut). The eel study was conducted in fresh water at 23 ± 1°C. In the intravenously administered groups flumequine was rapidly distributed to all major tissues and organs. After oral administration flumequine also appeared to have rapid and extensive absorption and distribution in all 3 species. After the distribution phase, the level of flumequine was higher in most organs and tissues than in the blood, except in muscle and brain. The most noticeable difference between the species was the slow elimination of flumequine from eel compared to turbot and halibut. In orally administered eels, substantial amounts of flumequine remained in all major organs/tissues for 7 d. At 28 d significant levels of flumequine were present in liver, kidney and skin (with traces in muscle), and at the last sampling point (56 d) in eye, bone, bile and posterior intestine. In orally administered turbot significant levels of flumequine were observed over 96 h in bile, urine, bone, skin, intestine and eye, and traces were detected over 28 d in bone and eye in addition to a significant level in bile. In orally administered halibut, significant levels of flumequine were observed in bile, skin, intestine and eye over 96 h. Traces were present in skin and eye over 7 d. The maximal flumequine concentrations in blood were calculated to be 2.5 mg equivalents l -1 (eel at 12 h), 0.8 mg l -1 (turbot at 6 h) and 0.6 mg l -1 (halibut at 6 h) after oral administration.