We studied the stability of amikacin and ciprofloxacin in in vitro coinfusion with two total parenteral nutrition. The antibiotic concentrations were determined by EMIT and HPLC for amikacin and ciprofloxacin, respectively. There were not significant differences between theoretical and measured concentrations. The emulsion stability were analyzed by visual inspection, Coulter-Counter and optic microscopy. The emulsion was stable and we didn't find any particle of size greater than 6 microns.