Oral rehydration solution (ORS) and zinc are the recommended treatment in developing countries for the management of uncomplicated diarrhoea in children under five (World Health Organization and UNICEF 2004). However, drug sellers often recommend costly and unnecessary treatments instead. This article reports findings from an experiment to encourage licensed chemical sellers (LCS) in Ghana to recommend ORS and zinc for the management of childhood diarrhoea. The intervention consisted of mobile phone text messages (Short Message Service or SMS) sent to a randomly assigned group of LCS who had been trained on the diarrhoea management protocols recommended by the World Health Organization (WHO). The SMS campaign comprised informational messages and interactive quizzes sent over an 8-week period. The study measured the impact of the SMS messages on both reported and actual practices. Analysis of data from both face-to-face interviews and mystery client visits shows that the SMS intervention improved providers’ self-reported practices but not their actual practices. The study also finds that actual practices deviate substantially from reported practices.