This study examines and characterizes the soft tissue wall of periodontal pockets after a 10-day in vivo exposure to monolithic tetracycline-impregnated fibers, with and without root planing. Four teeth from each of eight patients were randomly assigned to (1) nontreatment (controls), (2) treatment by root planing only, (3) treatment by tetracycline fiber only, or (4) treatment by scaling and root planing and tetracycline fibers. Ten days after initial therapy, all teeth were extracted with associated soft tissue pocket walls intact. Three specimens were obtained from each tooth for examination by scanning microscopy, energy dispersive spectroscopy, and light microscopy. Results indicated that use of tetracycline-impregnated fibers over a 10-day period did not adversely affect the epithelial lining and had no significant effect on the density or character of the inflammatory response present in adjacent soft tissue and confirmed the antimicrobial effects of the fibers.