The penetration of 1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl)-3-quinoline carboxylic acid (ciprofloxacin, Bay o 9867, Ciprobay) into parotid gland tissue and parotid saliva of the rat after intravenous administration (6 mg/kg body weight) was studied. 2 h after bolus injection ciprofloxacin mean levels in parotid gland tissue (0.60 mg/l) nearly reached 2-fold mean blood levels (0.36 mg/l). In parotid saliva the mean concentration of the gyrase inhibitor (0.20 mg/l) was lower than in blood, however, still high enough to be effective against the pathogens which most often cause inflammation of the parotid gland.