249 patients with well differentiated thyroid cancer attended the Nuclear Medicine Department of the Royal Liverpool Hospital (formerly housed at the Liverpool Clinic) from 1967 to 1990. Papillary carcinoma was histologically evident in 68% of patients and follicular carcinoma in 32%. Fifteen percent of all patients died of their cancer. The extent of initial surgery did not appear to influence the recurrence of disease, nor the patient survival. Univariate analysis showed that males had a worse survival rate than females during the 5 years after diagnosis but thereafter survival rates were similar. Multivariate analysis indicated that unfavourable survival factors were "age over 45 years at diagnosis" and "presence of distal metastases". Survival was not significantly different with or without 131I ablation where there were no distal metastases. Outcome of pregnancy after 131I ablation gave no cause for concern. No serious complications were observed following 131I therapy. Serum thyroglobulin tests were introduced only half way through the review period and were helpful in predicting the presence of tumour recurrence but these data are to be discussed in another communication.