| Kosi-Seemanchal | |
| Settlement Type: | Subregion |
| Subdivision Type: | Country |
| Subdivision Name: |  India |
| Subdivision Type1: | State |
| Subdivision Name1: | Bihar |
| Subdivision Type2: | Region |
| Subdivision Name2: | Mithila |
| Seat Type: | Largest city |
| Seat: | Purnea |
| Parts Type: | Divisions |
| Parts Style: | para |
| P1: | Kosi and Purnia |
| Unit Pref: | Metric |
| Demographics Type1: | Languages |
| Demographics1 Title1: | Spoken |
| Demographics1 Info1: | Maithili (including Thēthi), Surjapuri, Hindi, Urdu, English |
| Timezone1: | IST |
| Utc Offset1: | +5:30 |
| Blank Name Sec1: | Major highways |
| Blank Info Sec1: | ,,,, |
| Blank Name Sec2: | Major Railway Lines |
| Blank Info Sec2: | Barauni-Katihar, Saharsa and Purnia sections Barauni-Guwahati line |
Kosi-Seemanchal is a subregion of Mithila region[1] in the Northeastern part of Bihar. It consists of Kosi and Purnia divisions. It has seven districts — Araria, Madhepura, Saharsa, Supaul, Purnea, Kishanganj and Katihar.[2]