<b><i>Objective:</i></b> To report the speech performance and sound localization in adult patients 5 years after bilateral simultaneous cochlear implantation and to evaluate the change in speech scores between 1 and 5 years. <b><i>Design:</i></b> In this prospective multicenter study, 26 patients were evaluated 5 years after implantation using long straight electrode arrays (MED-EL Combi 40+, standard electrode array, 31 mm). Speech perception was measured using disyllabic words in quiet and noise, with the speech coming from the front and a cocktail party background noise coming from 5 loudspeakers. Speech localization measurements were performed in noise under the same test conditions. These results were compared to those obtained at 1 year reported in a previous study. <b><i>Results:</i></b> Five years after implantation, an improvement in speech performance scores compared to 1 year after implantation was found for the poorer ear both in quiet and in noise (+12.1 ± 2.6%, p < 0.001). The lower the speech score of the poorer ear at 1 year, the greater the improvement at 5 years, both in quiet (r = -0.62) and at a signal-to-noise ratio of +15 dB (r = -0.58). The sound localization on the horizontal plane in noise provided by bilateral implantation was better than the unilateral one and remained stable after the results observed at 1 year. <b><i>Conclusion:</i></b> In adult patients simultaneously and bilaterally implanted, the poorest speech scores improved between 1 and 5 years after implantation. These findings are an additional element to recommend bilateral implantation in adult patients. The use of both cochlear implants and speech training sessions for patients with poor performance should continue in the period after 1 year following implantation, since the speech scores will improve over time.