Current paediatric pulmonary hypertension (PH) diagnostic algorithms include some testing specifically for paediatrics, but it is unclear if this is used in clinical practice. We describe the current diagnostic workup of the TOPP (Tracking Outcomes and Practice in Paediatric Pulmonary hypertension) registry for suspected PH. We investigated 456 patients enrolled until February 2010. The majority had ECGs (94%), echocardiograms (96%) and/or chest radiographs (89%) performed and these were the noninvasive tests most frequently used for evaluation of suspected PH. No patient had all three tests considered normal, suggesting the potential for the combined use to rule out PH. For evaluation of complications associated with heart catheterisation (HC) we analysed a total of 908 HCs reported until February 2012. Of these, 554 were at diagnosis and 354 in follow-up. Complications were reported in 5.9% with five deaths considered related to HC, suggesting a higher rate of HC complications compared to adult studies. However, current recommendations support HC in paediatric PH. A proper application of the risk/benefit ratio for HC requires further data. Most children did not undergo the diagnostic workup currently recommended for adults, which highlights either incomplete awareness of current guidelines and/or challenges their appropriateness for children.