| Saint Martin | 0 | France | FR-MF |
| Saint Pierre and Miquelon | 0 | France | FR-PM |
| SAK | 0 | Russia | RU-SAK |
| Šakiai District Municipality | 0 | Lithuania | LT-41 |
| Sala Municipality | 0 | Latvia | LV-085 |
| Salacgrīva Municipality | 0 | Latvia | LV-086 |
| Salaspils Municipality | 0 | Latvia | LV-087 |
| Šalčininkai District Municipality | 0 | Lithuania | LT-42 |
| Saldus Municipality | 0 | Latvia | LV-088 |
| Šalovci Municipality | 0 | Slovenia | SI-033 |
| Salzburg | 0 | Austria | AT-5 |
| SAM | 0 | Russia | RU-SAM |
| San Ġwann | 0 | Malta | MT-49 |
| San Marino | 0 | San Marino | SM-07 |
| Sannat | 0 | Malta | MT-52 |
| Sant Julià de Lòria | 0 | Andorra | AD-06 |
| Santa Luċija | 0 | Malta | MT-53 |
| Santa Venera | 0 | Malta | MT-54 |
| Santarém | 0 | Portugal | PT-14 |
| SAR | 0 | Russia | RU-SAR |
| Saraj Municipality | 0 | Republic of North Macedonia | MK-68 |
| Sarajevo Canton | 0 | Bosnia and Herzegovina | BA-09 |
| Sarandë District | 0 | Albania | AL-SR |
| Sardinia | 0 | Italy | IT-88 |
| Satakunta | 0 | Finland | FI-17 |
| Saulkrasti Municipality | 0 | Latvia | LV-089 |
| Šavnik Municipality | 0 | Montenegro | ME-18 |
| SAW | 0 | United Kingdom | GB-SAW |
| SAY | 0 | United Kingdom | GB-SAY |
| SB | 0 | Romania | RO-SB |
| SC | 6 | United States | US-SC |
| SCB | 0 | United Kingdom | GB-SCB |
| Schaan | 0 | Liechtenstein | LI-07 |
| Schellenberg | 0 | Liechtenstein | LI-08 |
| SCT | 0 | United Kingdom | GB-SCT |
| SD | 0 | Moldova | MD-SD |
| SD | 4 | United States | US-SD |
| SD | 0 | Hungary | HU-SD |
| SE | 0 | Russia | RU-SE |
| Sēja Municipality | 0 | Latvia | LV-090 |
| Selnica ob Dravi Municipality | 0 | Slovenia | SI-178 |
| Semič Municipality | 0 | Slovenia | SI-109 |
| Semily | 0 | Czech Republic | CZ-514 |
| Šempeter–Vrtojba Municipality | 0 | Slovenia | SI-183 |
| Šenčur Municipality | 0 | Slovenia | SI-117 |
| Senglea | 0 | Malta | MT-20 |
| Šentilj Municipality | 0 | Slovenia | SI-118 |
| Šentjernej Municipality | 0 | Slovenia | SI-119 |
| Šentjur Municipality | 0 | Slovenia | SI-120 |
| Šentrupert Municipality | 0 | Slovenia | SI-211 |
| Serravalle | 0 | San Marino | SM-09 |
| Serres Prefecture | 0 | Greece | GR-62 |
| Setúbal | 0 | Portugal | PT-15 |
| Sevnica Municipality | 0 | Slovenia | SI-110 |
| Sežana Municipality | 0 | Slovenia | SI-111 |
| SF | 0 | Hungary | HU-SF |
| SFK | 0 | United Kingdom | GB-SFK |
| SFT | 0 | United Kingdom | GB-SFT |
| SG | 0 | Spain | ES-SG |
| SG | 0 | Switzerland | CH-SG |
| SGC | 0 | United Kingdom | GB-SGC |
| SH | 0 | Germany | DE-SH |
| SH | 0 | Hungary | HU-SH |
| SH | 0 | Switzerland | CH-SH |
| SH-AC | 0 | United Kingdom | GB-SH-AC |
| SH-HL | 0 | United Kingdom | GB-SH-HL |
| SHF | 0 | United Kingdom | GB-SHF |
| Shkodër County | 0 | Albania | AL-10 |
| Shkodër District | 0 | Albania | AL-SH |
| SHN | 0 | United Kingdom | GB-SHN |
| SHR | 0 | United Kingdom | GB-SHR |
| Shumen | 0 | Bulgaria | BG-27 |
| SI | 0 | Moldova | MD-SI |
| Šiauliai City Municipality | 0 | Lithuania | LT-43 |
| Šiauliai County | 0 | Lithuania | LT-SA |
| Šiauliai District Municipality | 0 | Lithuania | LT-44 |
| Šibenik-Knin County | 0 | Croatia | HR-15 |
| Sicily | 0 | Italy | IT-82 |
| Sigave | 0 | France | FR-WF-SG |
| Siġġiewi | 0 | Malta | MT-55 |
| Sigulda Municipality | 0 | Latvia | LV-091 |
| Šilalė District Municipality | 0 | Lithuania | LT-45 |
| Silistra Province | 0 | Bulgaria | BG-19 |
| Šilutė District Municipality | 0 | Lithuania | LT-46 |
| Širvintos District Municipality | 0 | Lithuania | LT-47 |
| Sisak-Moslavina County | 0 | Croatia | HR-03 |
| SJ | 0 | Romania | RO-SJ |
| SK | 5 | Canada | CA-SK |
| SK | 0 | Hungary | HU-SK |
| SK | 0 | Poland | PL-SK |
| Skåne County | 0 | Sweden | SE-M |
| Škocjan Municipality | 0 | Slovenia | SI-121 |
| Škofja Loka Municipality | 0 | Slovenia | SI-122 |
| SKP | 0 | United Kingdom | GB-SKP |
| Skrapar District | 0 | Albania | AL-SK |
| Skrīveri Municipality | 0 | Latvia | LV-092 |
| Skrunda Municipality | 0 | Latvia | LV-093 |
| Skuodas District Municipality | 0 | Lithuania | LT-48 |
| SL | 0 | Germany | DE-SL |
| SL | 0 | Poland | PL-SL |
