Triclosan (2,4,4'-trichloro-2'-hydroxydiphenyl ether) is an antibacterial agent included in dentifrices and mouth rinses. Previously, we reported that triclosan reduces the production of the inflammatory mediators in gingival fibroblasts. The aim of this study was to investigate the uptake, distribution, and release of (14)C-triclosan in gingival fibroblasts. Time-course studies showed that the uptake of (14)C-triclosan in cytoplasmic and nuclear fraction started within the first minute of incubation, increased gradually, and reached constant levels after 1 h in the nuclear fraction and slightly increased in the cytoplasmic fraction between 3 and 24 h. The distribution of (14)C-triclosan in the cytoplasmic and the nuclear fractions was, on an average, 84 and 16%, respectively. Autoradiographic results based on transmission electron microscopy confirmed the distribution of (14)C-triclosan in the cytoplasm and nucleus of the cell. The release of (14)C-triclosan showed that the radioactivity of the agent in the medium gradually increased during the first hour of incubation and then reached steady-state levels. After repeated washing of preloaded fibroblasts, the level of (14)C-triclosan in the cytoplasmic fraction decreased by 77% whereas the level in the nuclear fraction remained unchanged. Our results demonstrate that triclosan is distributed in the cytoplasm and remains associated with the nucleus of gingival fibroblasts, suggesting that the agent may affect the intracellular signal pathways involved in the production of inflammatory mediators.