Oster is a province (uezd) of the Chernigov government (guberniya), Ukraine.
Original Russian writing – Остеръ, German – Oster, English – Oster.
Post stamps
Stamps issued: 1.
The postage stamp was issued in 1885-1886 years (few unrecognized issues).
| Schmidt | Value | Year | Description | Rarity |
| 1 | 3 kop. | 1885 – 86 | Litho, 12 1/4 – 12 1/2 line perf., brown-red on white paper, white glue | 1/10 |
| 1I | 3 kop. | 1885 – 86 | same but brown or gray-brown. | 1/10 |
| 1I | 3 kop. | 1885 – 86 | same but bad perf. | 1/10 |
Sheets or largest known blocks
Block of 30, 6×5 stamps with 4 types (2×2).
Covers and stationary
Oster uezd produced covers with preprinted stamps with same stamp design.
Zemstvo postmarks
Only pen cancellations.