|Millennium:||1st millennium BC|
|Centuries:||5th century BC – 4th century BC – 3rd century BC|
|Decades:||360s BC 350s BC 340s BC – 330s BC – 320s BC 310s BC 300s BC|
|Years:||342 BC 341 BC 340 BC – 339 BC – 338 BC 337 BC 336 BC|
|339 BC by topic|
|Gregorian calendar||339 BC|
|Ab urbe condita||415|
|Ancient Egypt era||XXXI dynasty, 5|
|- Pharaoh||Artaxerxes III of Persia, 5|
|Ancient Greek era||110th Olympiad, year 2|
|Chinese calendar||辛巳年 (Metal Snake)
2358 or 2298
— to —
壬午年 (Water Horse)
2359 or 2299
|Coptic calendar||−622 – −621|
|Ethiopian calendar||−346 – −345|
|- Vikram Samvat||−282 – −281|
|- Shaka Samvat||N/A|
|- Kali Yuga||2763–2764|
|Iranian calendar||960 BP – 959 BP|
|Islamic calendar||990 BH – 988 BH|
|Minguo calendar||2250 before ROC
|Thai solar calendar||204–205|
|Wikimedia Commons has media related to 339 BC.|
Year 339 BC was a year of the pre-Julian Roman calendar. At the time it was known as the Year of the Consulship of Mamercinus and Philo (or, less frequently, year 415 Ab urbe condita). The denomination 339 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.
- Philip II of Macedon decides to attack the Scythians, using as an excuse their reluctance to allow Philip to dedicate a statue of Heracles at the Danube estuary. The two armies clash on the plains of modern-day Dobruja. The ninety-year-old King of the Scythians, Ateas, is killed during the battle and his army is routed.
- During a meeting of the Amphictyonic Council, Philip accuses the citizens of the town of Amfissa, in Locris, of intruding on consecrated ground. The Amphictyonic Congress, with the initial support of the Athenian representative, Aeschines, decides to inflict a harsh punishment upon the Locrians. After the failure of a first military excursion against the Locrians, the summer session of the Amphictyonic Council gives command of the league's forces to Philip and asks him to lead a second excursion. Philip acts at once, and his forces pass through Thermopylae, enter Amfissa and defeat the Locrians who are led by Chares, the Athenian general and mercenary commander.
- Xenocrates is elected as head of the Greek Academy replacing Speusippus.