First of all, you need to know that as a visitor in Australia, it is totally legal to get paid to do clinical trials just because it is not taxable. It's tax-free! Yeah! From what I could understand, there's two types of clinical trials. There's the healthy volunteer trials and the patient clinical trials. As a healthy participant, I applied on a trial for pulmonary arterial hypertension and I got a call back the day after. What happens is that they ask you some questions about your general health on the phone and if you pass these first requirements, they book you in for a screening. Screenings are basically where they run a couple of tests to see if you're truly eligible for the trial.