Up to 200 hooligans threw bottles and fireworks at police called to deal with the fight, and a police car was smashed up. One person was arrested and 45 people taken into custody.
Following the cancellation of the match after persistent rain, fans of both clubs gathered in various bars before converging on a St. Pauli fan bar. The attacks were reportedly started by Hamburger SV fans.
After the police initially diffused the situation, small bands of supporters of both teams then allegedly roamed the St. Pauli district.
The police had been expecting violence ahead of the derby. Police and stadium workers had already discovered fireworks attached to seats in the stands of Hamburg's Imtech Arena in the past few days.
Last September, the teams faced each other in the league for the first time in eight years. Fights between fans broke out ahead of the game.