Introduction. The prevalence of papillary thyroid carcinoma (PTC) in patients with primary hyperparathyroidism (PHPT) is low, it can be estimated around 2 to 4%. For unknown reasons it is higher than the prevalence of PTC in the overall population. The authors analyse the comorbidity of PTC with PHPT on patients treated in their institution. Material and method. The analysis covered medical records of 885 patients subject to the thyroid resection procedure and 95 patients operated for PHPT, the procedures were performed in years 2005-2014. Results. In the above-mentioned period there were 121 patients operated due to a malignant thyroid tumour and there were 95 patients that had surgery for PHPT. There were 4 cases of comorbidity of PHPT with papillary thyroid cancer. Prevalence of PTC at the patients with PHPT was 4.2%. In two out of the four cases, both diseases were diagnosed prior to the procedure and the single appropriate surgery i.e. total thyroidectomy and excision of parathyroid adenoma was performed. In the other two cases false positive localisation of parathyroid adenoma occurred due to metastatic cancerous lesions in cervical lymph nodes. The diagnosis of PTC was made postoperatively based on surgical specimen examination. Second surgical procedure appropriate for this diagnosis was necessary in both cases. Conclusions. The comorbidity of PHPT and PTC is clinically important and should be taken into account in the case of patients with PHPT and thyroid tumours. There is the possibility of false positive localization of parathyroid adenoma in the case of metastatic cancerous lesions in cervical lymph nodes.