Objective Cash transfer programmes targeting children are considered an effective strategy for addressing child poverty and for improving child health outcomes in developing countries. In South Africa, the Child Support Grant (CSG) is the largest cash transfer programme targeting children from poor households. The present paper investigates the association of the duration of CSG receipt with child growth at 2 years in three diverse areas of South Africa. Design The study analysed data on CSG receipt and anthropometric measurements from children. Predictors of stunting were assessed using a backward regression model. Setting Paarl (peri-urban), Rietvlei (rural) and Umlazi (urban township), South Africa, 2008. Subjects Children (n 746), median age 22 months. Results High rates of stunting were observed in Umlazi (28 %), Rietvlei (20 %) and Paarl (17 %). Duration of CSG receipt had no effect on stunting. HIV exposure (adjusted OR=2·30; 95 % CI 1·31, 4·03) and low birth weight (adjusted=OR 2·01, 95 % CI 1·02, 3·96) were associated with stunting, and maternal education had a protective effect on stunting. Conclusions Our findings suggest that, despite the presence of the CSG, high rates of stunting among poor children continue unabated in South Africa. We argue that the effect of the CSG on nutritional status may have been eroded by food price inflation and limited progress in the provision of other important interventions and social services.