The research aims at identify swimmers' start reaction time as a guide for training programs through comparing swimmers reaction between the four swimming methods,  different age stages, and gender in 50, 100 , and 200 meters swimming. 1-     Human domain: All swimmers participating in Sindelfingen International championship (13^thWorld Championship) at Germany, many clubs from many (65) countries had participated  in this championship including (9) clubs from Egypt, (2774) swimmers participated in this championship in different age stages divided into 5 categories as follows: (10-11) years stage (born in 1996-1997),  (12-13) years stage (born in 1994-1995),(14-15) years stage (born in 1992-1993)-, (16-17) years stage (born in 1990-1991)-,general (born in 1989 and before )2- ,Spatial Domain: Sindelfingen Club, Germany , Time-domain: from February 17^th, to February 18^th, 2007 , Conclusions:1- Reaction time in (10-11) age stage is less than (12-13), (14-15), (16-17) age stages and general in 50 meter races.2-     Reaction time in (12-13) age stage is less than (14-15), (16-17) age stages and general in 100 meters and 200 meters races, and  reaction time in (10-11) age stage is less than (16-17) age stage in 200 meter race3- There were no statistically significant differences between boys and girls in all races (50, 100, and 200 meters)4-  Reaction time in back stroke was less than other swimming method (free, butterfly and breast) in all races (50, 100, and 200 meters)5-  Reaction time in breast stroke was less than (free, butterfly) strokes in 50 meter race, also reaction time in butterfly stroke was less than free stroke in 50 meter race.6-     Reaction time in free stroke was less than butterfly stroke in 100 and 200 meter races, and less than breast stroke in 200 meter. Reaction time in breast stroke was less than butterfly stroke in 200 meter race.