Objective: To differentiate between benign and malignant hyperparathyroidism on the basis of excretion of HCG and its malignant isoforms in urine. Materials and Methods: This hospital based study was carried out using data retrieved from the register maintained in Manipal Teaching Hospital from $1^{st}$ January, 2008 and $31^{st}$ August, 2012. The variables collected were urinary HCG and HCG malignant isoform, calcium and parathyroid hormone. Preceding the study, approval was obtained from the institutional research ethical committee. Analysis was by descriptive statistics and testing of hypothesis. A p-value of <0.05 (two-tailed) was used to establish statistical significance. Results: Out of the 20 cases, 10 were primary hyperparathyroidism and the remainder were parathyroid carcinomas. The urinary HCG $6.1{pm}0.6$ fmol/mgCr was with in normal range in benign hyperthyroidism but was markedly elevated in three cases of malignant hyperparathyroidism (maximum value of excretion in urine for HCG was 2323 fmol/mgCr). The excretion of malignant isoform of HCG in urine was 0 in benign hyperparathyroidsm and in four cases of malignant hyperparathyroidism which fell into the category of persistantly low HCG. The maximum excretion of the malignant isoform of HCG in urine was 1.8, in the category of very high HCG. Calcium and parathyroid hormone were mildly raised in benign parathyroidism, while parathyroid hormone was markedly elevated in cases of malignant hyperparathyroidism falling into the category of very high HCG. Conclusions: The excretion of urinary HCG in urine has the ability to distinguish between parathyroid adenomas and carcinomas and thus has potential to become a marker of disease progression in malignant parathyroid disease.