This research aims to investigate whether multi/inter-disciplinary research activities are related to research impact and publication counts of scholars. Since researchers with very high levels of multi/inter-disciplinarity might be able to target complex problems, we would expect them to receive more credits than their colleagues with a stronger disciplinary orientation. We analysed Web of Science (WoS) indexed publications of all associate and full professors from a random sample of Australian universities in physics, chemistry and biology (1980–2014). Australian Fields of Research (FoR) codes assigned to journals were used to calculate the diversification of authors’ publications. The number of citations in the first 3 years, number of 10% most frequently cited papers, and citation impact percentile were used for impact assessment. A few indicators were used to measure the diversity including ‘extent of diversification (ED)’ (number of distinct FoR codes divided by the number of publications) and ‘diversification ratio (DR)’ (ratio of the publications falling outside the dominant code to the total number of publications). A total of 47.76% of biologists’ publications, 35.23% of physicists’ publications and 20.36% of chemists’ publications were published in journals assigned to fields other than the Australian associate and full professors’ fields. Publications from biologists had the largest values of diversification. Women (compared with men) and associate professors (compared with full professors) in chemistry, biology and overall were more probably to publish diversely. ED was negatively correlated with output and citation impact. DR also had a negative but weak correlation with the number of publications and 10% most frequently cited paper.