We investigated the serum free interleukin-18 [free state of interleukin-18 (IL-18)] concentration as a prognostic factor for hemodialysis patients' infection risk.<h4>Methods</h4>The Ibaraki Dialysis Initiation Cohort (iDIC) study is a multicenter prospective cohort investigation of patients undergoing a new initiation of dialysis in a local region of Japan. This evidence concerns the gene IL18 and infection.