Objective To analyze the frequency of blood pressure documentation performed by nursing professionals in an emergency department.Methods This is a cross-sectional, observational, descriptive, and analytical study, which included medical records of adult patients admitted to the observation ward of an emergency department, between March and May 2014. Data were obtained through a collection instrument divided into three parts: patient identification, triage data, and blood pressure documentation. For statistical analysis, Pearson’s correlation coefficient was used, with a significance level of α<0.05.Results One hundred fifty-seven records and 430 blood pressure measurements were analyzed with an average of three measurements per patient. Of these measures, 46.5% were abnormal. The mean time from admission to documentation of the first blood pressure measurement was 2.5 minutes, with 42 minutes between subsequent measures. There is no correlation between the systolic blood pressure values and the mean time interval between blood pressure documentations: 0.173 (p=0.031).Conclusion The present study found no correlation between frequency of blood pressure documentation and blood pressure values. The frequency of blood pressure documentation increased according to the severity of the patient and decreased during the length of stay in the emergency department.