Wayne and Barbara Tetzlaff sued Tim and Glenna Camp in 2003.
The Camps own a hog farm in Madison County. The Tetzlaffs sought damages for health problems, claiming they were the results of being exposed to manure spread on farm fields.
The case was moved to Polk County because of pretrial publicity.
This week, the jury found the Camps complied with rules and regulations.
It's believed to be 1 of the first cases in Iowa to center on health issues that could be caused by exposure to livestock manure.
The Camps' attorney, Brian Rickert, says the court allowed a pork producer to rely on the state's statutory nuisance defense. That provides protections for livestock producers who follow the law.
A telephone message left for Tetzlaff's attorney wasn't immediately returned.