The phenomenon of extra tuition is witnessed in many countries and some educationalists have described it as a parallel education system. However, the incidence and impact of extra tuition have often not been studied systematically, especially in Africa. In this article cross-national data for six African education systems (Kenya, Malawi, Mauritius, Namibia, Zambia and Zanzibar) collected by SACMEQ, the Southern and Eastern Africa Consortium for Monitoring Educational Quality, have been used to assess: (a) the incidence and growth of extra tuition, (b) the characteristics of students who received extra tuition, and (c) the association between extra tuition and student achievement. The analyses presented in this paper showed that extra tuition was a widespread phenomenon in all six education systems, and that receiving extra tuition was positively associated with the socio-economic levels of students' home backgrounds. The association between tuition and student achievement was mixed. The issues and challenges associated with tuition have been discussed and some suggestions for further research made.