Introduccion : el hiperparatiroidismo primario (HP) es una entidad clinica sintomatica o asintomatica, caracterizada por la produccion autonoma de parathormona (PTH). Se presenta elevacion del calcio serico y de la parathormona (PTH), aunque esta ultima puede permanecer dentro en los rangos normales altos. La gammagrafia de paratiroides es uno de los estudios imagenologicos que se utiliza para localizar las glandulas hiperfuncionantes. Casos clinicos: numero 1. Mujer de 69 anos, asintomatica, con hipertension arterial de reciente comienzo y osteopenia. PTHi y calcio serico elevados, fosforo disminuido. Ecografia de tiroides: bocio multinodular. Gammagrafia de paratiroides: hipercaptacion focal del trazador, inferior y lateralmente al lobulo derecho de la tiroides, compatible con adenoma paratiroideo. Realizada cirugia para reseccion. Diagnostico confirmado por hallazgos quirurgicos y de anatomia patologica. Numero 2. Mujer de 69 anos, hipertension cronica, antecedentes de tiroidectomia parcial y litotricia bilateral. Episodios de diarrea cronica y cefaleas. Endoscopia de vias digestivas superiores: duodenitis cronica erosiva. Endoscopia de vias digestivas inferiores normal. Elevacion de PTHi y calcio serico. TAC de cuello con contraste: lobulo derecho de glandula tiroides. Ecografia de tiroides igual resultado. Gammagrafia de paratiroides: tres areas de hipercaptacion focal, compatibles con hiperplasia glandular. Reseccion quirurgica, diagnosticos confirmados por cirugia y patologia. Conclusiones: la gammagrafia planar de paratiroides, de doble fase, doble trazador y tomografia SPECT, realizadas en combinacion, tienen buena sensibilidad, especificidad y exactitud diagnostica. Rev.cienc.biomed. 2012;3(2):350-354 PALABRAS CLAVES Hiperparatiroidismo; Gammagrafia; 99mTc-isonitrilos; Medicina nuclear; Adenoma de paratiroides; Hiperplasia paratiroidea. SUMMARY Introduction: primary hyperparathyroidism (PH) is a symptomatic or asymptomatic clinical entity, characterized by the autonomous production of parathyroid hormone (PTH). Its classical presentation exhibits an increase of the serum calcium and parathyroid hormone levels. Parathyroid scintigrafy, among other imaging modalities, is frequently used to detect the hyperfunctioning glands. Clinical case: number 1. Female, 69 years old, asymptomatic, hypertension of recent onset, osteopenia, increased intact PTHi level and serum calcium concentration, and low phosphate level, multinodular goiter (ultrasound), and focal increased uptake in the inferolateral aspect of thyroid right lobe (parathyroid scintigraphy) consistent with parathyroid adenoma, confirmed by surgery and histopathology examination. Number 2. Female, 69 years old, with history of chronic hypertension, nephrolithiasis and partial thyroidectomy, actually with chronic diarrhea and headaches, erosive chronic duodenitis (endoscopy), increase of PTHi and serum calcium levels, changes in contrast neck CT scan and US consistent with thyroidectomy, and parathyroid scintigraphy with three areas of focal increased isonitrile uptake consistent with parathyroid hyperplasia, confirmed by surgery and histopathologic findings. Conclusion: the parathyroid Scintigraphy (planar and Spect, double phase and double tracer) done in combination, have good sensibility, specificity and diagnostic accuracy of parathyroid adenomas and hyperplasia, improving surgical procedures, with minimal incision or invasion, ad quality of life of hyperparathyroidism patients. Rev.cienc. biomed. 2012;3(2):350-354 KEYWORDS Hyperparathyroidism; Radionuclide Imaging; 99mTc-isonitrilos; Nuclear medicine; Parathyroid neoplasms; Parathyroid disease.