Objectives: We investigated weight gain effects of the Bofesungjangjeungbo-tang ($Bcheck{u}fgrave{e}ichacute{e}ngzhcheck{a}ngzar{e}ngbcheck{u}$-tang) on thin Korean preschool children with frequent common cold or chronic rhinitis Methods Bofesungjangjeungbo-tang was empirically composed of 14 herbs for treating indigestion, and common cold or chronic rhinitis. We analyzed 60 preschool children who have visited Kim Kijoon Oriental Clinic BOM from Jan. 1, 2006 to Aug. 31, 2011 with three criteria: 1) 2~5yrs of age and BMI<50th percentile 2) children those who had taken the Bofesungjangjeungbo-tang for 1~3 month (s), 3) Availability of records on before/after treatment within 3 months. Weight gain of the children after treatment was evaluated by the changes of BMI percentile compared to pre-treatment. Results Bofesungjangjeungbo-tang significantly improved BMI percentile in all groups (1 month: $21.33{pm}10.04$ vs $26.43{pm}13.16$, p<0.001; 2 months: $21.90{pm}10.28$ vs $29.03{pm}15.06$, p<0.001; 3 months: $19.06{pm}10.04$ vs $35.71{pm}17.40$, p=0.001). Gender, age and pre-treatment BMI had no significant effects on the effectiveness of Bofesungjangjeungbo-tang. Conclusions: Bofesungjangjeungbo-tang positively affected weight gain in 2~5yrs Korean preschool children with BMI below 50 percentile within 1~3 month (s) of treatment. However, additional studies on functional dyspepsia or the change of energy intake are needed to understand the factors related to weight gains.