Year 34 (XXXIV) was a common year starting on Friday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Persicus and Vitellius (or, less frequently, year 787 Ab urbe condita). The denomination 34 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.
- Paullus Fabius Persicus and Lucius Vitellius become Roman consuls.
- Construction of a three-tier Roman aqueduct beginning in Nîmes and running for 269 miles.
- Naevius Sutorius Macro is said to gain favour in the empire by prostituting his wife Eunius to Caligula.
- St. Paul and St. Barnabas start preaching the gospel to the Gentiles.
- Roman intervention in Armenia (34–37).
- The original inhabitants of Dacia revolt against the Sarmatian tribe of Iazyges who had enslaved them.
- Aulus Persius Flaccus, Roman poet (d. 62 AD)
- Stephen, the first martyr of Christianity (stoned to death by Jewish leaders for preaching that Jesus was the Christ)
- Jesus (approximate date)