Abstract Background: Handgrip strength is a crucial indicator of upper extremity muscular strength and is vital for monitoring disorders like cardiac diseases that restrict a patient’s physical activity and result in muscle atrophy. The aim of our study was to evaluate whether muscle strength loss is present in patients with pulmonary hypertension and whether this test can be an alternative to 6-minute walk test. Materials and methods: The study included 39 healthy children who were admitted to the outpatient clinic and 16 children with a diagnosis of pulmonary hypertension who were being followed in our centre. We assessed the differences in upper extremity handgrip strength using the Jamar Hydraulic Hand Dynamometer device among both healthy children and those diagnosed with pulmonary hypertension. Moreover, we compared the handgrip strength of pulmonary hypertension patients with significant prognostic indicators such as NYHA class, 6-minute walk test, and pro-brain natriuretic peptide. Results: The mean dominant handgrip strength was 20.8 ± 12 kg in the patient group and 21.6 ± 12.4 kg in the control group (p = 0.970). Handgrip strength was shown to be negatively connected with pro-brain natriuretic peptide (r = −0.565, p = 0.023) and positively correlated with 6-minute walk test (r = 0.586, p = 0.022) during the patient group evaluation. Conclusion: Six-minute walk test needs a customised physical area (30 m of a straight hallway) and trained personnel for applying the test. The handgrip strength test, a different muscle strength indicator, can be used to more clearly and simply indicate the decline in patients’ ability for effort. Additionally, it was found in our study that handgrip strength decreased as pro-brain natriuretic peptide levels rose, a crucial measure in the monitoring of pulmonary hypertension.