Objectives: This study sought to evaluate the incidence of cardiorenal syndrome (CRS) type 1 in a coronary care unit and its association with hospital mortality within 30 days of admission, as well as other epidemiological characteristics. Methods: The medical records of all the patients who were hospitalized with the diagnosis of acute heart failure in a 4-year period were reviewed. CRS type 1 was characterized by the presence of acute heart failure and an elevation of serum creatinine ≥ 0.3 mg/dL in comparison to the baseline creatinine calculated by the MDRD75 equation and/or the elevation of ≥ 50% of the admission serum creatinine within a 48 h period. Results: The incidence of CRS type 1 was 27.87%, 95% CI: 20.13-36.71 (34 of 122). There was a higher frequency of CRS type 1 in those patients who were admitted with the diagnosis of cardiogenic shock (adjusted RR 2.02, 95% CI: 1.20-3.93, p = 0.0378) and in those with higher hemoglobin levels (p = 0.0412). The CRS type 1 was associated with an increase of 30-day mortality (HR: 4.11, 95% CI: 1.20-14.09, p = 0.0244). Conclusions: The incidence of CRS type 1 in the coronary care unit found in our study is similar to those found in foreign studies. The history of stroke and the higher values of hemoglobin were associated with a higher incidence of cardiorenal syndrome type 1. Patients with CRS type 1 had a higher hospital mortality within 30 days of admission.