OBJECTIVES: The objective of this qualitative interview study was to assess the content validity of the BII in a sample of men with signs and symptoms of BPH using concept elicitation (CE) and cognitive interviewing (CI) methods. METHODS: Fifty men with BPH participated in the study; 27 completed the CEs and 23 completed the CIs. CEs were semi-structured asking subjects to describe the BPH symptoms they experience and how symptoms impact their life. CIs were semi-structured, asking subjects to describe their 1) difficulties completing the BII; 2) understanding of item meaning and terminology; 3) understanding of response options; and 4) ability to respond appropriately to the specified recall period. All interviews were audio recorded and transcribed. Data was analyzed using Atlas.ti. A saturation table was used to identify when no new concepts were forthcoming. Inter-rater agreement (IRA) was evaluated by having three coders independently dual-code 3 (11%) transcripts. Consistency of coding was characterized by agreement in the identification of concepts, and agreement in assignment of codes. RESULTS: Saturation of concepts was reached by the completion of 21 CE interviews. High agreement on coding consistency was achieved at 69.4 to 89.4% for identification of concepts, and 87.8 to 96% for assignments of codes. The BII was shown to be readily understandable and easily completed in a short period of time, and supported by the qualitative results as measuring the relevant impacts related to BPH. CONCLUSIONS: The BII shows strong evidence of content validity and provides an assessment of disease-related, clinically meaningful impacts of BPH symptoms and treatment outcomes in BPH studies.