Background Ambiguity and uncertainty are inherent within the practice of medicine. While theory suggests the construct may be multidimensional, scales such as the Tolerance of Ambiguity of Medical Students And Doctors (TAMSAD) act unidimensionally, at least in a local population. Therefore, the dimensionality of the Tolerance of Ambiguity (ToA) construct remains unclear. This study aims to explore the dimensionality of ToA in early postgraduate doctors using the TAMSAD scale in a UK national sample and consider the implications of this dimensionality for theory and practice. Methods We used data from 428 respondents in a national research project examining the experiences of newly qualified doctors in the UK (2020). We undertook an exploratory factor analysis (extracting one-factor to six-factor solutions) of the 29-item TAMSAD scale and compared findings to an existing integrative model of uncertainty tolerance. Results The analysis suggested that the ToA construct is multidimensional. The three-factor model and five-factor model provided clinically interpretable factors and had different merits. It appears that having an affinity for complexity is not simply the opposite of experiencing discomfort from uncertainty, and that a professional’s epistemological beliefs about the nature of medicine may influence their ToA. Conclusions These findings support an extension to a key integrative model of uncertainty tolerance, and support development of interventions to increase ToA in doctors. For example, through encouraging increased reflection on an individual’s own epistemological beliefs about medicine and the role of doctors. The potential impact of such interventions can be evaluated using scales such as the TAMSAD.