To determine whether the Scottish protocol for follow-up of complex renal cysts is effective in identifying advancing disease requiring treatment Ensure patients do not progress beyond treatment during follow-up To determine an appropriate length of follow-up for complex renal cysts in Scotland Findings are in keeping with Bosniak's research, suggesting that 5–8% of patients with Bosniak IIF cysts develop into malignant disease 1 INTRODUCTION The Bosniak classification of renal cysts was...