| POS | ATHLETE | COUNTRY | MARK | Reaction Time | 
|---|---|---|---|---|
| 1 | Jamaica Junior |  JAM | 43.85 Q SB | 0.150 | 
| 2 | Great Britain & N.I. Junior |  GBR | 44.49 Q PB | 0.162 | 
| 3 | France Junior |  FRA | 45.24 q | 0.186 | 
| 4 | Finland Junior |  FIN | 45.63 q | 0.142 | 
| 5 | South Africa Junior |  RSA | 46.03 q | 0.146 | 
| Australia Junior |  AUS | DQ | 0.156 | 
| POS | ATHLETE | COUNTRY | MARK | Reaction Time | 
|---|---|---|---|---|
| 1 | United States Junior |  USA | 43.92 Q | 0.178 | 
| 2 | Germany Junior |  GER | 45.77 Q | 0.141 | 
| 3 | Switzerland Junior |  SUI | 45.96 q SB | 0.142 | 
| 4 | Saint Kitts and Nevis Junior |  SKN | 46.14 NJ | 0.192 | 
| 5 | Senegal Junior |  SEN | 47.55 NJ | 0.158 | 
| Canada Junior |  CAN | DNF | 0.170 |