|Millennium:||1st millennium BC|
|Centuries:||3rd century BC – 2nd century BC – 1st century BC|
|Decades:||200s BC 190s BC 180s BC – 170s BC – 160s BC 150s BC 140s BC|
|Years:||178 BC 177 BC 176 BC – 175 BC – 174 BC 173 BC 172 BC|
|175 BC by topic|
|Gregorian calendar||175 BC|
|Ab urbe condita||579|
|Bahá'í calendar||−2018 – −2017|
|English Regnal year||N/A|
|Chinese calendar||乙丑年 (Wood Ox)
2522 or 2462
— to —
丙寅年 (Fire Tiger)
2523 or 2463
|Coptic calendar||−458 – −457|
|Ethiopian calendar||−182 – −181|
|- Vikram Samvat||−118 – −117|
|- Shaka Samvat||N/A|
|- Kali Yuga||2927–2928|
|Igbo calendar||−1174 – −1173|
|Iranian calendar||796 BP – 795 BP|
|Islamic calendar||820 BH – 819 BH|
|Minguo calendar||2086 before ROC
|Thai solar calendar||369|
|Wikimedia Commons has media related to 175 BC.|
Year 175 BC was a year of the pre-Julian Roman calendar. At the time it was known as the Year of the Consulship of Scaevola and Lepidus (or, less frequently, year 579 Ab urbe condita). The denomination 175 BC for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.
- King Seleucus IV of Syria arranges for the exchange of his brother Antiochus for Demetrius, the son of Seleucus IV, who has been a hostage in Rome following the Treaty of Apamea in 188 BC. However, Seleucus IV is assassinated by his chief minister Heliodorus who then seizes the Syrian throne.
- Antiochus manages to oust Heliodorus and takes advantage of Demetrius' captivity in Rome to seize the throne for himself under the name Antiochus IV Epiphanes.
- During this period of uncertainty in Syria, the Egyptian ruler, Ptolemy VI, lays claim to Coele Syria, Palestine, and Phoenicia, which the Seleucid king Antiochus III has previously conquered. Both the Syrian and Egyptian parties appeal to Rome for help, but the Roman Senate refuses to take sides.
- Timarchus is appointed governor of Media in western Persia by Antiochus IV to deal with the growing threat from the Parthians while Timarchus' brother, Heracleides, becomes minister of the royal finances.
- The construction of the western front of the altar in Pergamum, Turkey begins (approximate date) and is finished in 156 BC. A reconstruction of it is now kept at the Staatliche Museen zu Berlin, Preussischer Kulturbesitz, Pergamonmuseum in Berlin.