Many of the most serious crimes that can be committed in South Africa are, since 1998, subject to mandatory minimum sentences prescribed in legislation. This legislation was originally introduced as a short-term measure, yet has now become a permanent fixture. This article looks critically at the mandatory sentencing legislation in South Africa, drawing comparisons with similar legislation in Australia. It also examines some of the consequences of such legislation not properly foreseen in South Africa, in particular the escalation in the prison population. In taking an internationally comparative approach, this article contributes to the contemporary debate on mandatory sentencing.