Malaria is one of the leading public health problems and causes of morbidity and mortality in Sudan. High-quality malaria diagnosis is important in all settings as misdiagnosis can result in significant morbidity and mortality. Accuracy of rapid diagnostic test is questionable in children and adults in Sudan. The present study was conducted to assess the performance of malaria rapid diagnostic test (SD Pf) in children and adults in Sennar locality. Cross-sectional study was conducted in Sennar Pediatric Teaching and Sennar Teaching Hospitals. In this study the performance of RDT Pf was compared with microscopy of Giemsa-stained blood films. In children the sensitivity of RDT was 92.8% and specificity was 92.3%, while in adults it was 76.8% and 94.8%, respectively (P-value = 0.00). In overall study, statistical analysis showed the presence of weak positive correlation between parasite density and RDT result (0.0101, P-value = 0.088). That means, the level of parasitaemia did not affect the result of RDT in both children and adults.