The South African Medicines Control Council (MCC) policy that trial participants be paid a flat rate of R150 per visit in clinical trials has been criticised in the press. (1) The literature argues that it is an excessive or inappropriate reward; (2) it neglects salient factors such as the design or nature of the study, (2,3) and non-industry-funded trials may not be able to afford it. (3) Also, this amount could be regarded as an ‘undue inducement’ for participants to enrol. In our view, the main problem is that the MCC policy violates the ethical principle of justice in that participants are paid the same amount but do not do the same things or incur the same expenses. (4) It has been argued that it would be more appropriate to have a broad contextualised policy (5) and that participants should be paid for their time and expenses. (2) To take these recommendations forward, we apply two theoretical models of payment (the Wage Payment and Reimbursement models) for time, inconvenience and expenses (TIE). We recommend that participants be paid for their time at a rate similar to national unskilled labour rates, with increments for inconvenient procedures (determined nationally), and that they are refunded their direct expenses; this is operationally complex but ethically sound.