Research on tacrolimus class of antibiotics spans 25 years. Each of the nine analogues in the Tacrolimus Analogue Set represent a pivotal advance in the development of the tacrolimus class, with the analogues displaying a range of physico-chemical and potency profiles. The Tacrolimus Analogue Set is a useful tool in addressing current research questions, using the resources accumulated since the discovery of tacrolimus in 1986 and recognising its relationship to the antifungal actives, ascomycin and rapamycin, discovered decades earlier.