| Ostrow Mazowiecka to Oerlinghausen | 560.24 mi (901.62 km) |
| Ostrow Mazowiecka to Oestrich-Winkel | 628.45 mi (1,011.39 km) |
| Ostrow Mazowiecka to Offenburg | 679.86 mi (1,094.12 km) |
| Ostrow Mazowiecka to Oftersheim | 623.42 mi (1,003.30 km) |
| Ostrow Mazowiecka to Ohrdruf | 495.50 mi (797.43 km) |
| Ostrow Mazowiecka to Ohringen | 592.76 mi (953.95 km) |
| Ostrow Mazowiecka to Olbernhau | 394.79 mi (635.36 km) |
| Ostrow Mazowiecka to Olching | 562.46 mi (905.19 km) |
| Ostrow Mazowiecka to Oldenburg | 569.08 mi (915.85 km) |
| Ostrow Mazowiecka to Oldenburg in Holstein | 463.44 mi (745.83 km) |
| Ostrow Mazowiecka to Olfen | 617.41 mi (993.63 km) |
| Ostrow Mazowiecka to Olpe | 611.07 mi (983.42 km) |
| Ostrow Mazowiecka to Olsberg | 577.62 mi (929.58 km) |
| Ostrow Mazowiecka to Oranienburg | 361.87 mi (582.38 km) |
| Ostrow Mazowiecka to Ortenberg | 575.89 mi (926.81 km) |
