Text Box: INVESTIGATION OF THE BREAST DEVELOPMENT AND SERUM LEPTIN LEVELS IN GIRLS OF 2~13 YEARS AGE IN SHANGHAI Ni JH, Wang DF, Wang W, Cui YF, Wang XM, Jing J Children Growth and Development Center, Rui Jin Hospital, Shanghai Second Medical University, China Objective: To investigate  The age of onset of breast devilment and the related factors ‚ the serum leptin levels revealed by girls with idiopathic central precocious puberty (ICPP) and premature thelarche (PT). Method: 11132 2~13 years age girls were investigated. Breast development was staged according to modified Tanner scale. Serum leptin levels were measured using RIA from 20 girls 6~9 years age with PT or ICPP. Results:  Prevalence of breast development among age groups of 2~3 and 4~7 years were 0.87% and 1.7% respectively; 19% being found in group of 8~9 years (B2 69.5%, B4~5 2.6%), 72.4% in age group of 10~13 years with B2, B3, B4~5 (31.6%, 50.5% and 17.9% respectively). ‚ Factors suspected of breast development were as maternal menarche age, intake of high animal proteins, supplementary tonic or nourishment ƒ 37 girls with PT show their body height ³1SD, BA>CA in 68%, peak response of FSH>LH by LHRH stimulating test in 90%. „ The serum levels of PT and ICPP were all significantly higher than these of age- matched non-pubertal girls, without significant difference between PT and ICPP groups. Conclusion: girls aged 4~7 years with precocity of breast development mostly associated with other signs suspected of initiation of CPP which needs close survey. As leptin may well be a permisive factor for the initiation of sexual development, elevation of serum leptin level in PT girls may serve as early additive sign for evaluation of ICPP in occurrence. 2361