Estudio de la consistencia interna y estructura factorial de tres versiones de la escala de Zung para ansiedad

background: the zung's rating instrument for anxiety disorders has been used in various colombian researches. its internal consistency and factor structure have not been reported among university students. objective: to calculate the internal consistency and explore the factor structure of three versions of the zung's rating instrument for anxiety disorders among university students. method: two-hundred twenty-one medicine and psychology students of a private university in cartagena completed the 20-item version of the zung's rating instrument for anxiety disorders. the mean of age of students was 20.5 (sd=2.6), 64.4% were women, and 54.3% studied medicine. cronbach alpha was computed and exploratory factor analysis was done for three versions. results: the 20-item version of the zung's rating instrument for anxiety disorders presents cronbach alpha coefficient of 0.77 and three principal factors accounted for 40.1% of the total variance. the 10-item version showed cronbach alpha of 0.83 and two-dimensional structure responsible of 54% of the total variance. the 5-item version showed cronbach alpha of 0.74 and one-dimensional structure accounted for 49.5% of the total variance. conclusions: the 10- and 5-item version of the zung's rating instrument for anxiety disorders present better psychometric properties than the original 20-item version. it is necessary to estimate the properties of these versions compared with a criterion reference.