The Female Sexual Function Index (FSFI; Rosen et al., 2000) and International Index of Erectile Function (IIEF; Rosen et al., 1997) are two of the most widely used measures of sexual dysfunction. However, they have potential measurement and psychometric flaws that have not been addressed in the literature. This article examines the measurement capabilities of these measures based on data collected from an online study in 2010. A convenience sample of 518 sexually active adults (65% female) drawn from the general community were included in the analyses. Both measures displayed critical theoretical and measurement problems for the assessment of sexual problems beyond sexual arousal, and for the sexual desire domains in particular. Based on these results, we encourage clinicians and researchers to think critically about whether the FSFI and IIEF are appropriate measures for their practice and research. In particular, these measures are inappropriate for use among individuals who are not currently sexually active, and research with a focus other than sexual arousal should consider supplementary measures of sexual function. The psychometric properties of these measures should be reassessed in clinical samples, but the theoretical issues with the measures raised in this article are relevant across clinical and research contexts.