The use of paper health records and handwritten prescriptions are prone to preset errors of misunderstanding instructions or interpretations that derive in affecting patients’ health. Electronic Health Records (EHR) systems are useful tools that among other functions can assists physicians’ tasks such as finding recommended medicines (and their contraindications) and dosage for a given diagnosis, filling prescriptions and support data sharing with other systems. By using an EHR many errors can be avoided. This paper presents EEMI (Expediente Electrónico Médico Infantil), a Children EHR focused on assisting pediatricians in their daily office practice. EEMI functionality keeps the relationships among diagnosis, treatment, and medications. EEMI also calculates dosages and automatically creates prescriptions which can be personalized by the physician. The system also validates patient allergies to avoid prescription of any pharmaceutical with alerts. EEMI was developed based on the experience of pediatricians in the Monterrey metropolitan area. This paper also presents the current use of EHRs in Mexico, the Mexican Norm (NOM-024-SSA3-2010), standards for the development of electronic medical records and its relationships with other standards for data exchange and data representation in the health area. This system is currently in production. It uses novel technologies such as cloud computing and software services