Abstract: Frequencies of thyroid problems in different age, sex and seasons were determined from the relative concentration of thyroid hormones (T3 and T4) and thyroid stimulating hormone (TSH) in 9054 patients. These patients visited the radioimmunoassay (RIA) laboratory of the Institute of Radiotherapy and Nuclear Medicine (IRNUM) Peshawar during the years 1984-1990 (except 1987) and 1995 and 1996. The patients were classified into infants, children, adults and old age groups according to their age, into males and females according to their sex and into winter, spring, summer and autumn according to their visit to the laboratory. T3 and T4 in the blood serum of these patients were determined by radioimmunoassay (RIA) and their TSH in the blood serum were determined by immuno-radiometric assay (IRMA). The data revealed that 54% thyroid patients were having normal levels of T3, T4 and TSH. Considering all age groups together, the frequencies of hyperthyroidism/Thyrotoxicosis and hypothyroidism were 5.1 and 4.0% respectively. Similarly, the frequencies of subclinical hyperthyroidism and subclinical hypothyroidism were 5.8 and 5.4% respectively. The frequencies of other thyroid problems were 25.8%. The frequency of hyperthyroidism/ thyrotoxicosis was higher in adults group (2.9%) followed by old age group (2.0%), children group (0.2%) and infants group (0.01%). Similarly the frequency of hypothyroidism was higher in adults group followed by old age group, children group and infants group were 1.8, 1.3, 0.7, 0.1% respectively. Similar pattern of frequencies of subclinical hyperthyroidism, subclinical hypothyroidism and other thyroid problems was observed. Iodized salted should be used only in iodine deficient areas and with caution.