To monitor deficient or excessive intakes of biologically available fluoride (F), various biological samples have been tested for use as biomarkers of human exposure to F. Most such studies have concerned children and often have only involved measurement of F in one or two types of sample. The present study investigated the relationships of F concentrations in biomarkers of F exposure including plasma, saliva, hair, finger- and toenails, and daily urinary fluoride excretion (UFE) with the total daily fluoride intake (TDFI) of adults. TDFI was assessed in 60 healthy adults, aged >= 20 years; 31 lived in a low-fluoride water area (LFA, 0.04 mg F/L) and 29 in a high-fluoride water area (HFA, 3.05 mg F/L) of Nigeria. All volunteers provided at least one biomarker sample from the above list and completed a questionnaire to evaluate fluoride intake from the diet and toothpaste ingestion. TDFI, UFE and F concentrations of biomarkers were statistically significantly higher in the HFA than in the LFA. There were strong statistically significant positive correlations between TDFI and UFE (ρ = 0.730, p < 0.001); plasma F (ρ = 0.729, p < 0.001); fasting whole saliva F (ρ = 0.653, p < 0.001) and hair F (ρ = 0.603, p < 0.001). The statistically significant positive correlations between TDFI and fingernail F (ρ = 0.502, p < 0.001) and between TDFI and toenail F (ρ = 0.556, p < 0.001) were moderate. In conclusion, this study has indicated the usefulness of 24h UFE as well as fluoride concentration in plasma, fasting whole saliva and hair as biomarkers of contemporary or sub-chronic F exposure in groups of adults. However, they do not appear to have the necessary sensitivity to predict F exposure in individuals.