| Code | Name | Region |
|---|---|---|
| DEOIM | Ostelsheim | BW |
| DEONS | Osten | MV |
| DE69X | Ostenfeld | SH |
| DEOB4 | Osterbinde | NI |
| DEQOG | Osterburg | ST |
| DEO5M | Ommersheim | SL |
| DEOTK | Oortkaten | HH |
| DEOPB | Opfenbach | BY |
| DELVO | Opladen | NW |
| DEOPC | Oppach | SN |
| DE79V | Oppelsbohm | BW |
| DEOPU | Oppenau | BW |
| DEOPP | Oppenheim | RP |
| DEOPE | Oppenweiler | BW |
| DEOPN | Oppin | ST |
| DEOPG | Oppurg | TH |
| DEONB | Oranienbaum | ST |
| DEORA | Oranienburg | BB |
| DEORC | Orbis | RP |
| DE59E | Oring | SH |
| DEO6M | Ormont | RP |
| DE2OB | Ornbau | BY |
| DEOGZ | Orsingen-nenzingen | BW |
| DEORS | Orsoy | NW |
| DEONR | Ortenberg | BW |
| DENNR | Olbronn-durrn | BW |
| DEOLC | Olching | BY |
| DEOLO | Oldenburg | NI |
| DEOLH | Oldenburg In Holstein | SH |
| DEOLB | Oldenbuttel | SH |
| DE76D | Oldendorf | NI |
| DEOLD | Oldendorf | NI |
| DE67U | Oldendorf | SH |
| DEODO | Oldendorf (luhe) | NI |
| DEOB8 | Oldersbek | SH |
| DEOLU | Oldersum | NI |
| DEODS | Oldinghausen | NW |
| DEODL | Oldisleben | TH |
| DEOLW | Olfen | NW |
| DEOLE | Olpe | NW |
| DEOLP | Olpenitz | SH |
| DEOLS | Olsberg | NW |
| DEOLJ | Olsbrucken | RP |
| DE73Z | Olsburg | NI |
| DEOLZ | Olzheim | RP |
| DEOAM | Offenbach Am Main | HE |
| DEODQ | Offenbach An Der Queich | RP |
| DEOFR | Offenberg | BY |
| DEOFG | Offenburg | BW |
| DEOFH | Offenhausen | BY |