The aim of this was to compare the efficacy of photobiomodulation after non-surgical mechanical debridement (MD) on cortisol levels (CL) in peri-implant sulcular fluid (PISF) among patients with peri-implant mucositis. Patients with peri-implant mucositis were encompassed. All patients underwent non-surgical MD with (test group) and without (control group) a single application of photobiomodulation. Demographic data were collected and PISF was collected. Peri-implant modified plaque index (mPI), modified gingival index (mGI), probing depth and crestal bone loss were measured, and CL in PISF were recorded. All clinical parameters and PISF CL were re-assessed at 4months of follow-up. p<.05showed statistical significance. Seventeen (14 males and 3 females) and 17 (15 males and 2 females) patients with peri-implant mucositis were recruited in test and control groups. The mean age of patients in the test and control groups was 46.1±6.5 and 50.2±2.7years respectively. At baseline, mPI, mGI, PD and PISF volume and CL in control and test groups were similar. At follow-up, there was a significant reduction in mPI (p<.001), mGI (p<.001), PD (p<.001) and PISF volume (p<.001) and CL (p<.001) in both groups compared with baseline. There was no difference in mPI, mGI, PD and PISF volume and CL in test and control groups at follow-up. In short term, non-surgical MD with photobiomodulation does not offer additional benefits in terms of reducing soft-tissue inflammatory parameters and PISF CL in patients with peri-implant mucositis.