Reported here is the case of a 5-year old boy with a pyeloureteral junction (PUJ) obstruction and pyelonephritis caused by Actinobaculum schaalii, an Actinomyces-like organism. Pyelonephritis or any other urinary tract infection caused by Actinobaculum schaalii has not been described in children before. The patient responded well to pyeloplasty in combination with antibiotic treatment.