Aim of our study has been the systematic evaluation concerning the still farmost unknown disease of postoperative, permanent hypoparathyroidism. For this we designed a specific questionnaire as measuring instrument--it was evaluated by experts and validated by 3 control groups--to examine then a patient group (n = 20) with symptomatic postoperative, permanent hypoparathyroidism. The application of the questionnaire was very feasible, the reliability of measuring scales according to Cronbach's alpha > or = 0.70. The validity of content and construct validity fully existed (Pearson's correlation coefficient r > or = - 0.27; p < 0,05). The farmost frequent clinical complaints were peripheral cold sensations (65 %), pains in joints (55 %), sensation of heaviness and weakness in extremities (55 %) and paresthesias (45 %). Most frequent clinical symptoms were brittle nails (40 %) and diarrhoea (35 %). Sum and distress level scores for classification of illness severity were determined. In conclusion our questionnaire is a valid instrument and from a clinical point of view easy to apply, reasonable and very feasible in practical use. It represents a novel, optimum instrument to determine disease condition and illness severity of hypoparathyroid patients and makes it possible to gain further information of this up to now less systematically analysed disease.