An number of potential drugs are extremely water insoluble, limiting their commercialisation as medicines. Solubilisation of drug in surfactant micelles is a means of increasing the apparent aqueous solubility of a drug and ensuring exploitation as a medicine. Micelles formed by the anionic surfactant, sodium dodecyl sulphate, are an excellent solubiliser of poorly soluble steroidal drugs (testosterone enanthate, 4-cholesten-3-one and adrenosterone). However, changing the anion grealty influences solubilisation with lithium increasing and ammonium decreasing solubilisation in the doecyl sulphate micelle. Using SANS with contrast variation we aim to probe the effect of counterion on the structure of the surfactant micelle in solution, and the way in which the drug is solubilised, thereby aiding in the rationale design and selection of surfactants to optimise drug solubilisation.