Introduction: Bacterial resistance is a global phenomenon, but it presents geographic and temporal variations; this is the importance of local surveillance programs.Objective: To determine trends in antibiotic resistance in hospitals between 2007 and 2012 in Medellín and its Metropolitan Area.Materials and methods: Percentages of antibiotic resistance between 2007 and 2012 in 22 institutions were obtained using WHONET 5.6 program. For interpretation of susceptibility results, CLSI standardsof 2009 and 2012 were used. Using the Epi-Info 6.04 program a trends analysis of antibiotic resistance was done using the chi-square for linear trend with a confidence level of 95%, a value of p≤0.05 was considered significant.Results: In six years of surveillance of antibiotic resistance we found a decrease of oxacillin resistance in Staphylococcus aureus (p=0.0006) and an increase of vancomycin resistance in Enterococcus faecium (p=0.0000). In Escherichia coli and Serratia marcescens an increase of resistance to ceftazidime was found, in contrast to a decrease in Klebsiella pneumoniae (p=0.0000) and Enterobacter cloacae (p=0.058). K. pneumoniae, S. marcescens and E. cloacae showed an increase of carbapenem resistance in contrast to a reduction of carbapenem resistance in Pseudomonas aeruginosa and Acinetobacter baumannii.Conclusions: The resistance surveillance identified important findings as the emergence of E. faecium resistant to vancomycin and carbapenem-resistant Enterobacteriaceae. It is essential to determine the antibiotic use in the region to establish their influence on the resistance profiles, as well as ensuring the quality of information and microbiological procedures in the microbiology laboratories.