Postoperative complications after surgery in the mandible are still a clinical problem. Levels of four antibiotics--azidocillin, erythromycin, doxycycline and clindamycin--were measured in serum, dental alveolar serum, saliva and mandibular bone in 24 patients undergoing surgical removal of mandibular third molars. The concentration in mandibular bone for azidocillin was 0.8 microgram/g +/- 0.4 microgram/g, erythromycin 0.2 microgram/g +/- 0.1 microgram/g, doxycycline 2.6 microgram/g +/- 2 microgram/g and clindamycin 0.6 microgram/g +/- 0.4 microgram/g. No saliva levels were achieved with azidocillin and erythromycin, whereas doxycycline and clindamycin gave measurable saliva levels.