The Multidimensional Inventory of Hypochondriacal Traits (MIHT; Longley, Watson, & Noyes, 2005) appears to address shortcomings of other common measures of health anxiety, but further research is required prior to using this measure in treatment planning and outcome assessment. This study was designed to explore the hierarchical structure of this health anxiety measure and relations of the various MIHT health anxiety components to anxiety sensitivity. A sample of 535 university students (362 women) was administered the 31-item MIHT and the 16-item Anxiety Sensitivity Index (ASI; Reiss, Peterson, Gursky, & McNally, 1986). Confirmatory factor analyses of participants’ responses on the MIHT showed that this measure may be conceptualized either as involving four correlated factors (i.e., Affective, Cognitive, Behavioral, and Perceptual) or as being hierarchical in nature, with the four lower-order factors loading on a single higher-order global health anxiety factor. Correlational analyses revealed significant relations of anxiety sensitivity to each of the four MIHT subscales and to the MIHT total score. Of the three established anxiety sensitivity components, ASI Physical Concerns were most strongly and consistently related to the various dimensions of health anxiety on the MIHT. Additional analyses revealed that the ASI and MIHT are better represented as two correlated but independent traits as opposed to common manifestations of a single underlying trait.