The ability of fibroblasts attach to teeth is of paramount imporance in re-establishing the lost connective tissue attachment after periodontal therapy. Tobacco contains a complex mixture of substances including nicotine. various nitrousamines, trace elements. and a variety of poorly characterized substances. The effects of nicotine on fibroblasts have reported an altered morphology and attachment of fibroblasts to substrates and disturbances in protein synthesis and secretion. This study examined the effect of nicotine, a major component of the particulate phase of tobacco smoke, on human gingival fibroblasts and periodontal ligament cells attachment to tissue culture surfaces and cellular activity of human gingival fibroblasts and periodontal ligament cells. Pooled human gingival fibroblasts made from extraction of 3rd molar were utilized between passage 4 and 5 and plated in 96 well plate at 20,000 cells per well. Cell number were determined using 3-(4,5-dimethylthiazole-2-y)2,5-diphenyltetrazolium bromide(MTI) , which is reflection of mitochondrial dehydrogenase activity. The concentration of nicotine used were 0.025, 0.05, 0.1, 0.2 and $0.4{mu}M$, the average serum concentration for a smoker being approximately $0.1{mu}M$. The results were as follows : 1. Attachment effects of nicotine on human gingival fibroblasts and periodontal ligament cells Excepts of $0.4{mu}M$, the effects on attachment with increasing numbers of cells attaching with increasing nicotine concentrations, compared to control group. But over the 60min, return to control value. 2. The effect of cellular activity on human gingival fibroblasts and periodontal ligament cells. The cellular activity of human gingival fibroblasts and periodontal ligament cells were similar or decrease to control value at 1st incubation day. At 2nd incubation day, 0.05, 0.1, 0.2, $0.4{mu}M$ concentrations were statistically different from control value on gingival fibroblasts group. But at 3rd incubation day, cellular activities of all experimental group were significantly decrease than control group.