| POS | BIB | ATHLETE | COUNTRY | MARK | Reaction Time | 
|---|---|---|---|---|---|
| 1 | 590 | Novlene Williams-Mills |  JAM | 49.66 Q SB | 0.206 | 
| 2 | 677 | Ana Guevara |  MEX | 50.19 Q SB | 0.213 | 
| 3 | 259 | Ilona Usovich |  BLR | 50.31 q NR | 0.182 | 
| 4 | 556 | Joanne Cuddihy |  IRL | 50.73 NR | 0.167 | 
| 5 | 473 | Lee McConnell |  GBR | 51.07 SB | 0.217 | 
| 6 | 362 | Indira Terrero |  CUB | 51.08 | 0.164 | 
| 7 | 968 | Natasha Hastings |  USA | 51.45 | 0.163 | 
| 8 | 609 | Asami Chiba |  JPN | 51.81 SB | 0.199 | 
| POS | BIB | ATHLETE | COUNTRY | MARK | Reaction Time | 
|---|---|---|---|---|---|
| 1 | 474 | Nicola Sanders |  GBR | 49.77 Q PB | 0.174 | 
| 2 | 793 | Natalya Antyukh |  RUS | 49.93 Q SB | 0.190 | 
| 3 | 1003 | Deedee Trotter |  USA | 50.31 q | 0.179 | 
| 4 | 592 | Shericka Williams |  JAM | 50.37 SB | 0.181 | 
| 5 | 229 | Christine Amertil |  BAH | 51.18 | 0.209 | 
| 6 | 570 | Daniela Reina |  ITA | 51.99 SB | 0.198 | 
| 7 | 542 | Barbara Petráhn |  HUN | 52.12 | 0.195 | 
| 8 | 535 | Aliann Pompey |  GUY | 53.58 | 0.193 | 
| POS | BIB | ATHLETE | COUNTRY | MARK | Reaction Time | 
|---|---|---|---|---|---|
| 1 | 477 | Christine Ohuruogu |  GBR | 50.16 Q PB | 0.200 | 
| 2 | 1006 | Mary Wineberg |  USA | 50.27 Q | 0.185 | 
| 3 | 839 | Tatyana Veshkurova |  RUS | 50.71 | 0.172 | 
| 4 | 267 | Amantle MONTSHO |  BOT | 50.90 NR | 0.242 | 
| 5 | 589 | Shereefa Lloyd |  JAM | 51.00 PB | 0.179 | 
| 6 | 703 | Christy Ekpukhon Ihunaegbo |  NGR | 51.60 | 0.184 | 
| 7 | 779 | Ionela Târlea |  ROU | 51.62 | 0.152 | 
| 8 | 360 | Aymeé MartÃnez |  CUB | 57.77 | 0.321 |