In this work the design and development of a system to monitor tremors in patients with Parkinson's disease based on Arduino open-source prototyping platform is presented. For processing data tremors acquired by the sensor device we have developed an Android application which allows an evaluation of the state of PD patients based on three types of tests that are in the Unified Parkinson's Disease Rating Scale recommended by the Movement Disorder Society (MDS-UPDRS); the tests performed in the application are: postural tremor of the hands, kinetic tremors of the hands and resting tremor amplitude. The results of PD Patients showed that despite receiving medication to minimize symptoms of their disease, patients have a considerable tremor amplitude, which affects the normal development of their daily activities. In addition, the spectral analysis of the tremors shows that two of the patients were correctly diagnosed with PD while the third patient showed spectral characteristics which led us to suggest to the treating physician reconsider the diagnosis.