Pseudohypoaldosteronism Type II (PHAII) is a very rare disorder characterized by hyperkalemia, hypertension, and slight hyper-chloremic metabolic acidosis. The index patient showed typical features of PHAII, including elevated blood pressure (140-150/90-100 mmHg), hyperkalemia in the range of 5.30-5.60 mmol/l (normal range is 3.50-5.10 mmol/l), accompanied by hyperchloremia of 109.5-112.0 mmol/l (normal 95.0-108.0 mmol/l) and acidosis with bicarbonate levels of 19.5-20.1 mmol/l (normal 22.0-27.0), GFR was 98.95 ml/min (normal > 90). However, these features were absent in his parents. Sequencing analysis found the patient with a WNK4 gene mutation, 1682 C > T in Exon 7, which resulted a missense mutation at codon 561 (P561L). The variation in codon 561 was not found in his parents and 100 unrelated control subjects. The identified WNK4 mutation which has not been described previously is the probable cause of PHAII.