There is an urgent need for the development of effective antibacterial coatings to cope with more and more resistant bacterial strains in medical environments, and particularly to prevent nosocomial infections following bone implant surgery. Polyelectrolyte multilayers (PEMs) based on poly-l-lysine (PLL) and complexes of poly(acrylic acid) (PAA) and gentamicin have been fabricated here applying the layer-by-layer (LbL) technique. Complexes are prepared by mixing PAA and gentamicin solutions in 500 × 10−3m NaCl at pH 4.5. The assembly of PLL and the complexes follows an exponential growth allowing a high loading of gentamicin in a four bilayer PEM. Although PEMs are stable and do not degrade at physiological pH, there is a continuous release of gentamicin at pH 7.4. PEMs show an initial burst release of gentamicin in the first 6 h, which liberates 58% of the total gentamicin released during the experiment, followed by a sustainable release lasting over weeks. This release profile makes the coating appealing for the surface modification of bone implants as a high concentration of antibiotics is necessary during implant surgery while a lower antibiotic concentration is needed until tissue is regenerated. PEMs are effective in preventing the proliferation of the Staphylococcus aureus strain.