The 1991 Holsten International, also known as the European Indoor Championships, was an ATP men's tennis tournament held at the Deutschlandhalle in Berlin, Germany. The tournament was played on indoor carpet and was held from 8 October until 15 October 1991.
| 1991 Holsten International | |
|---|---|
| Date | 8–15 October |
| Edition | 2nd |
| Draw | 32S / 16D |
| Prize money | $260,000 |
| Surface | Carpet / indoor |
| Location | Berlin, Germany |
| Venue | Deutschlandhalle |
| Champions | |
| Singles | |
 Petr Korda[1] | |
| Doubles | |
| Petr Korda / Karel Nováček[2] | |
Petr Korda won his eighth career title and his fourth of the year by defeating Arnaud Boetsch in the final.[3]
Finals
Singles
Petr Korda defeated 
Arnaud Boetsch, 6–3, 6–4
- It was Korda's 2nd singles title of the year and of his career.
Doubles
Petr Korda / Karel Nováček defeated 
Jan Siemerink / Daniel Vacek, 3–6, 7–5, 7–5