Background. The medical record represents the transcript of the pathologic narrative of a patient. Our aims were: to identify the most common abbreviations present in medical records; to identify discouraged abbreviations; to identify polysemic abbreviations; and to show the distribution of the abbreviations according to the type of ward (medical-surgical). Methods. An observational, descriptive and retrospective study by auditing the digital clinical records of patients discharged from FuenlabradaUniversityHospital in 2013 was conducted. Abbreviations in discharge reports and medical order prescriptions present in 78 medical records, corresponding to 39 men and 39 women of different services, were reviewed. Results. All medical records showed abbreviations. The mean of abbreviations in each medical record was 38.9±17.7. Medical records showed 688 different abbreviations, which were repeated up to a total of 3,038 times. The most frequent abbreviations were HTA (n=98; 3.23%), AP (n=89; 2.93%). Twenty-eight abbreviations considered unsafe appeared and were repeated 646 times. The most frequent included SC (n=63; 9.75%), ui (n=49; 7.59%),> (n=38; 5.88%), mcg (n=36; 5.57%). Twenty-three polysemic abbreviations were also identified, the most frequent being H (n=117; 12.81%), MC (n= 109; 11.94%), MP (n=99; 10.84%). Finally, medical wards had 1,866 abbreviations and surgical 1,172 (P <0.001). Conclusions. All medical records revised included unsafe abbreviations. The use of unsafe abbreviations was common among medical services.