Police dressed in riot gear arrested two people on weapons charges and three for disorderly conduct after an argument at the counter-protest, the Milwaukee Journal Sentinel reported.
A commotion started after a group of neo-Nazi sympathizers were confronted by a group of angry protesters. Insults were yelled back and forth and someone threw a metal object, the newspaper said.
The National Socialist Movement, a neo-Nazi group out of Detroit, organized the rally to call attention to instances of violence this summer, including so-called flash mobs of young African-Americans attacking white adults at the Wisconsin State Fair in West Allis.
The neo-Nazi ranks numbered 25 to 30, while the counter-protest had about 2,000 in attendance. One hundred police patrolled the area, keeping the two groups separate.
No one was injured at either protest.
"I'm pretty proud of West Allis today," resident Darryl Nitsch, 49, said.