The association of a toxic multinodular goitre with papillary thyroid carcinoma and primary hyperparathyroidism is very rare. Only one case is reported in the literature, we present the second one. It is a 51 year old woman, who initially presented with a toxic nodular goitre. The diagnosis of primary hyperparathyroidism was made following renal complications and the discovery of papillary thyroid carcinoma was incidental during the surgical treatment of parathyroid adenoma. Whilst the association of those three diseases is exceptional, the coexistence of any two of them is relatively frequent without any known common etiopathogenetis. It is recognised that hyperparathyroidism can be found in hyperthyroid patients, but the diagnosis of hyperparathyroidism in these cases is very difficult. The fortuitous discovery of papillary thyroid carcinoma during parathyroid surgery has already been reported but in most cases it is a microcarcinoma. In patients presenting with hyperthyroidism the risk of an associated carcinoma is generally felt to be negligeable. However, this associations is not rare. The association of primary hyperparathyroidism, hyperthyroidism and papillary carcinoma of the thyroid is rare. However, the authors suggest that the presence of any of the pathologies should trigger a search for the other two.