['No foolproof preoperative diagnostic indicators of parathyroid carcinoma (PC) exist in absence of nonskeletal metastases. Palpable parathyroid tumor, advanced skeletal and renal manifestations, and very high serum calcium and parathyroid hormone levels are considered strong predictors. Most of these features are common in Indian primary hyperparathyroidism (PHPT) patients although only few have PC. The aim of this study was to identify dependable clinicoinvestigative predictors of PC in Indian PHPT patients.', 'Clinical, biochemical, radiological, and densitometric attributes of 100 PHPT patients who underwent successful parathyroidectomy (1990-2004) were studied. Various parameters of patient groups with parathyroid adenoma (n = 84), primary hyperplasia (n = 12), and carcinoma (n = 4) were compared using ANOVA, with P value < 0.05 considered significant.', 'Mean age of patients was 37.4 years, with no difference in the 3 groups (P = 0.92). Patients in 3 groups had comparably severe bone disease; 36 had coexistent renal disease. Two patients with PC and 27 (32%) with adenoma had palpable parathyroid tumor. None of the biochemical parameters predicted malignant pathology. Mean tumor weight (milligram) in carcinoma patients (15,080 +/- 5,638.02) was significantly higher than those with adenoma (5,724 +/- 1,257.9) (P = 0.002). Postoperative course and recovery in carcinoma patients were similar to those with adenoma. In follow-up (mean: 33 months), none of the adenoma patients were found to have persistent/recurrent PHPT attributable to missed PC.'] Do indian primary hyperparathyroidism patients with parathyroid carcinoma differ in clinicoinvestigative characteristics from those with benign parathyroid pathology?