Acute rheumatic fever (ARF), affecting mainly poor Maori and Pacific populations, can lead to rheumatic heart disease (RHD) requiring heart operations, and decreased life expectancy. Some children have episodes of undetected heart inflammation, leading to RHD, without being unwell in childhood. RHD can be detected with a 5-minute heart scan using portable ultrasound (echo). Penicillin prevents progression of heart problems but it is unproven whether echo-detected RHD is as serious as that following an episode of classical ARF. A programme of echo screening to detect RHD has already been undertaken in 5 regions in New Zealand and the planned research will re-examine the screened RHD children to confirm how serious echo-detected RHD becomes. The risk of RHD in families of RHD children will also be examined. Benefits and harms of echo screening will be determined to ascertain if this is an acceptable and safe public health tool.