| Valea Boului | |
| Name Other: | Bătrâna |
| Pushpin Map: | Romania |
| Subdivision Type1: | Country |
| Subdivision Name1: | Romania |
| Subdivision Type2: | Counties |
| Subdivision Name2: | Buzău, Brăila |
| Subdivision Type3: | Villages |
| Subdivision Name3: | Costieni, Ziduri, Bălăceanu, Galbenu, Jirlău |
| Length: | 53km (33miles) |
| Mouth: | Buzău |
| Mouth Location: | Vișani |
| Mouth Coordinates: | 45.1518°N 27.2949°W |
| Basin Size: | 420km2 |
| Tributaries Left: | Sinești |
| Tributaries Right: | Cochirleanca |
The Valea Boului (also known as Bătrâna) is a left tributary of the river Buzău in Romania. It discharges into the Buzău in Vișani.[1] Its length is 53km (33miles) and its basin size is 420km2. It flows through Lake Jirlău.