An emerging literature in behavioural ethics conceptualized ethical sensitivity as a critical part of the decision making process. Ethical sensitivity together with an understanding of the client, their needs, emotions and circumstances is fundamental to an effective therapeutic relationship and competent practice. This study appears to be the first to empirically measure this concept in decision making related to the therapeutic sciences, including audiology, occupational therapy, physiotherapy and speech-language therapy. A multidisciplinary measure of ethical sensitivity is developed and consists of 12 vignettes that represent clinically relevant ethical issues related to these four professions. The study followed a two-phase, sequential mixed-methods research approach. Phase 1, the qualitative stage, focused on developing a measuring instrument by means of a systematic review of the following: ethical codes of conduct; focus group discussions; individual in-depth interviews; an expert panel review; and public complaints websites. Phase 2, the quantitative stage, focused on implementing and evaluating the measuring instrument. One hundred participants representing the four professions completed the instrument. Participants' overall scores on the Measuring Instrument for Ethical Sensitivity in the Therapeutic sciences (MIEST) were comparable for all four professions, confirming the multidisciplinary usability of the instrument. Participants were inclined to make grounded Beneficence centred decisions. Participants were particularly sensitive about the impact of the therapist's actions on the individual client, and sometimes overlooked their duty to the community. The MIEST can be used to assess the ethical sensitivity of student therapists (and possibly qualified therapists) and describe the stage of their ethical sensitivity development throughout the course of their professional development. The constructed vignettes make the MIEST appropriate for use in problem-based learning programmes.