| Ialomicioara | |
| Name Other: | Vaca |
| Pushpin Map: | Romania |
| Subdivision Type1: | Country |
| Subdivision Name1: | Romania |
| Subdivision Type2: | Counties |
| Subdivision Name2: | Dâmbovița County |
| Subdivision Type3: | Villages |
| Subdivision Name3: | Ferestre, Runcu, Fieni |
| Length: | 27km (17miles) |
| Mouth: | Ialomița |
| Mouth Location: | Fieni |
| Mouth Coordinates: | 45.1167°N 25.4178°W |
| Basin Size: | 95km2 |
| Tributaries Left: | Valea Babei, Valea Orlei, Dulbanu, Crângul Mușii |
| Tributaries Right: | Valea Frumușelului, Pârâul Stroiei, Negrița, Homoriciu |
| Custom Label: | River code |
| Custom Data: | XI.1.7 |
The Ialomicioara is a right tributary of the river Ialomița in Romania. It discharges into the Ialomița at Fieni.[1] The upper reach of the river is also known as Vaca. Its length is 27km (17miles) and its basin size is 95km2.