BACKGROUND: This study was undertaken to investigate, the effect of 6 weeks treatment with acetaminophen (AAP) and fluoride (F), administered either separately or together, on nitric oxide generation, lipid and protein peroxidation, total antioxidant status and level of reduced glutathione in the liver and kidney of male and female Wistar Han rats. Also, the influence of AAP on F excretion in urine was determined. METHODS: Thirty adult male and female rats were divided into five equal groups of six each: (I) controls drinking tap water; (II) controls drinking tap water and receiving 1 ml of tap water intragastrically; (III) animals receiving 12 mg F/L in drinking water; (IV) animals receiving 150 mg AAP /kg b.w./day; (V) animals receiving 12 mg F/L in drinking water and 150 mg AAP /kg b.w./day. RESULTS: F and AAP given separately and both together enhanced oxidative and nitrosative stress in investigated tissues. No gender differences were observed in oxidative/nitrosative stress parameters during treatment with F and/or AAP. Interestingly, the combined exposure to F and AAP resulted in an enhancement of oxidative/nitrosative stress in kidney of male and female rats compared to the group treated separately with F and AAP. No additive effect in the measured parameters in the liver during co-exposure to both xenobiotics was noticed. CONCLUSIONS: As expected, the urinary F excretion increased in an exposure time-dependent manner in rats receiving F or a combination of F and AAP. The study also showed that AAP significantly decreased urinary F.