Objective: To compare the speech perception outcomes for patients with preoperative severe versus profound hearing loss with a cochlear implant (CI). Study Design: Retrospective patient review. Setting: Cochlear implant program. Patients: Cochlear implant adult recipients (16 yr and above) having surgery between 2008 and 2015 with speech perception results and four frequency averaged severe (70-89 dBHL) or profound (90 dBHL and above) hearing loss. Prelingual deaf adults were included in the data. Intervention: Cochlear implant. Main Outcome Measures: Speech perception scores with CUNY sentences and monosyllabic (CNC/CVC) word scores at preoperative and 3, 6, and 12 months postoperatively testing. Mann-Whitney U test was performed to compare outcomes of the two groups. Interquartile comparisons were also made. Results: The severe group had significantly better speech perception than the profound hearing loss group for CUNY sentences and CNC/CVC word scores preoperatively (p < 0.001) (p < 0.001), at 6 months (p < 0.001) (p < 0.001), and at 12 months (p < 0.01) (p < 0.001), respectively. At 3 months there was no significant difference. The number of patients in each severe or profound group at the different time points ranged from 92 to 367 patients for CUNY sentences and from 52 to 216 patients for the word scores. The 12 months' lower quartile score for CUNY sentences for severe and profound groups was 83% and 75% respectively. The lower quartile score for words was 32% and 26% respectively. Conclusion: Adult CI recipients showed marked improvements in speech perception with a CI. Those with severe hearing loss have significantly better outcomes compared with profound hearing loss patients. These outcomes can inform CI candidacy evaluation criteria.