Pseudohypoparathyroidism (PHP) is characterized by end organ resistance to parathyroid hormone (PTH). PHP type Ia consists of Albright's osteodystrophy and resistance to PTH. In PHP type Ib physical appearance is normal and there is no response to PTH in U-cAMP excretion. In PHP type II both physical appearance and U-cAMP response to PTH infusion are normal. Two adolescent patients with severe hypocalcaemia were treated in our department. The first boy was admitted because of low back pain, latent tetany and recurrent collapsing, the second one due to Grand mal epilepsia. S-Ca concentrations were very low (1.1 and 1.03 mmol/l respectively), CT of the brain revealed multiple calcifications in basal ganglia and S-PTH concentrations were above upper reference level. Therefore the diagnosis of PHP was established. In the absence of skeletal malformations the most probable diagnosis is PHP Ib or II. Clinical state of the boys has dramatically improved after calcium and vitamin D supplementation.