For biometric study on the widlth of mouth in singaporian the author measured the transversal width of mouth, Longitudinal width of mouth and Interdental space in 652 cases of the total cases 317 were male (chinese 235. malay50, Indian 32) and 335 Female (Chinese 260, malay 53. Indian 22) and Ages ranged from 5 to 25 yeass old. The fallowing result was obtained. 1) In Adult, transversal width of mouth was 54. 20±0.22mm in male, 53.00±0.10mm in female and 40.03±0.26mm in male, 39.39±0.30mm in female of children. 2) In Abult, Longitudinal width of mouth was 52.00±0.12mm in male, 48.40±0.15mm in female and 44.50±0.13mm in male 44.20±0.30mm in female of children. 3) In Adult, Interdental Space (anterior teeth) was 44.20±0.15mm in male. 44.00±0.20mm in Fmale and 38.40±0.15mm in male, 37.17±0.21mm in Female of Children.