OBJECTIVES: As an indicator that concept elicitation study results are robust and trustworthy, the value of demonstrating saturation (i.e., the point at which no new information is gained from conducting additional interviews) in qualitative research is widely accepted. Nevertheless, there is little empirical evidence to guide researchers in making a prioridecisions regarding sample size in such studies. This study sought to assist in providing such evidence.    METHODS: A retrospective analysis of saturation results from n=26 concept elicitation studies completed between 2006 and 2013 was conducted.  Studies included a total of n=633 subjects (57% female), representing a spectrum of therapeutic categories, ages (M=47.5 [SD] 17.2 years), ethnicities (33% non-Caucasian), and education status (25.8% with high school degree or less).  The vast majority of the interviews were conducted in the US (99.2%) across 25 states.  Study sample sizes ranged from 10-43 (M=20.9 [SD] 8.1).  Across all studies, 432 symptom concepts (range 7-33, M=16.6 [SD] 6.4) were elicited.  Each sample was divided into quartiles based on the chronology of individual interviews.   Study results (i.e., patient reports) were then reviewed to determine the interview number and quartile in which each concept was first elicited.   RESULTS: Analysis showed that 84.0% (n=363), 92.4% (n=399), 97.2% (n=420), and 99.3% (n=429) of all elicited concepts had emerged by the tenth, fifteenth, twentieth, and twenty-fifth interview, respectively.  Less than 1% (n=3) of concepts emerged after the 25^thinterview in samples with >25 subjects. CONCLUSIONS: While a variety of factors inform sample size decisions in concept elicitation interview studies, this analysis suggests that researchers can reasonably expect to elicit 95% to 100% of the targeted disease-related symptoms-level concepts, and thus achieve saturation, through the conduct of 20 to 25 interviews.