Introduction: incidence of gastric cancer has increased in many countries including Colombia, showing high prevalence, and remains the second Ieading cause of cancer mortality in the world. In recent years a new facilitating diagnostic and treatment too), immunohistochemistry testing to determine the frequency of the gene encoding epidermal growth factor 2 (HER2) overexpression in both surgical and biopsy specimens may be used in order to deliver HER2-positive gastric cancer targeted therapy with trastuzumab. Objective: to determine the frequency of HER2 overexpression in gastric cancer in our hospital, as well as to obtain local data on epidemiologic features. Methodology: from 2005 to 2009, 58 samples obtained by biopsy or gastrectomy were diagnosed as gastric adenocarcinoma at the pathology labo­ ratory. HER2 testing by inmmunohistochemistry was conducted in ali 58 samples. Results: out of 58 samples, 27 were biopsies and 31 were gastrectomies predominantly gastric antrum intestinal-type adenocarcinoma. Five cases were HER2 positive, 51 were HER2 negative and 2 were undetermined. Conclusio11: frequency of HER2 overexpression of cases included in this study is Iow, comparable to nearly the lower limit described in literature.