In 14 healthy volunteers (8 M and 6 F), aged 19 to 33 years, serum and salivary concentrations of ofloxacin, administered in a single oral dose of 300 mg, were measured by high performance liquid chromatography (HPLC) and the microbiological agar diffusion method. The serum peak was observed at hour 1 (2.61 +/- 0.17 micrograms/ml), with a T1/2 of 4.14 h, a Kel of 0.167 h-1 and AUC of 15.07 micrograms/ml.h. The peak salivary concentration, obtained at hour 2, was 1.96 micrograms/ml, with a T1/2 of 4.40 h. Twenty dental patients (12 M and 8 F), aged 18 to 37 years, with various diseases, were treated orally with ofloxacin 600 mg/day for a period of four to six days. The clinical response proved excellent in one case, good in 16, fair in two and poor in one, with 85% efficacy rating. In five of these patients, ofloxacin concentrations in gingival tissue and alveolar bone were found to be 1.90 +/- 0.09 micrograms/g and 1.58 +/- 0.06 micrograms/g, respectively, while serum and salivary assays by HPLC confirmed the previous results. No changes of importance in haematochemical parameters were found in any of the patients. One patient only presented with diarrhoea and a skin rash which promptly cleared on discontinuing the therapy. Ofloxacin for its spectrum of action and good diffusion in the salivary and parodontal tissue compartment can be considered an useful tool in oral chemo-antibiotic therapy.