News site globoesporte reported that the incident occurred after Recife club Santa Cruz drew 1-1 with visitors Parana in a second division match.
There were clashes outside the Arruda stadium and fans ripped toilet bowls out and threw them at rivals on the streets below.
"In front of Gate 6 there was a big fight that resulted in the death of the fan," police captain Wilson Queiroz was quoted as saying. "The toilet was thrown from the stands and hit him full on.
"The victim was with someone at the time but everyone fled the scene after the incident."
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The death is the latest shock to Brazil in the run-up to this summer's World Cup.
The country is racing to get ready to host the tournament in June and July but preparations have been marred by delays, cost overruns, construction accidents and protests.
Daily shootouts and recent police slayings of two alleged drug traffickers rattled two of Rio de Janeiro's most prominent slums earlier this year, while at least 39 homicides were committed during a two-day police strike in and around the northeastern city of Salvador.
There have also been several fatal accidents during the construction of stadiums around the country.
FIFA President Sepp Blatter has encouraged fans to be optimistic that the World Cup in Brazil will be a success, despite growing concerns over security and public unrest as workers scramble to finish stadiums on time.
- Sports & Recreation