| Competition: | OB I |
| Season: | 1918 |
| Winners: | Ferencváros |
| Prevseason: | 1917 |
| Nextseason: | 1919 |
1918 Országos Bajnokság I (men's water polo) was the 12th water polo championship in Hungary. There were two teams who played one match for the title.
| Team | M | W | D | L | G+ | G− | P | |
|---|---|---|---|---|---|---|---|---|
| 1. | Ferencvárosi TC | 1 | 1 | 0 | 0 | 7 | 1 | 2 |
| 2. | MAFC | 1 | 0 | 0 | 1 | 1 | 7 | 0 |
* M: Matches W: Win D: Drawn L: Lost G+: Goals earned G−: Goals got P: Point