BACKGROUND : The aim of the current review was to answer the P.I.C.O.S question: In patients with post endodontic pain (Population), what is the effect of phototherapy (Intervention) as compared to placebo (Comparator) on post endodontic pain (Outcomes) considering only randomized clinical trials-RCT (Study design)? METHODS : The outline of this systematic review followed the PRISMA (Preferred Reporting Items for Systematic Review and Meta-Analysis) guidelines. Main databases [MEDLINE (1952-February 2019), EMBASE (1984-February 2019), Cochrane Central Register of Controlled Trials and Cochrane Oral Health Group Trials Register (1993- February 2019)] were searched. PEP was selected as the main outcome variable. The details of the data from the accepted studies were charted according to the research designs, author/country, demographics, involvement of teeth, phototherapy administration, follow-up duration, main results and PEP outcomes. RESULTS : A total of 5 RCTs were included. The wavelengths of diode lasers ranged from 808 to 970 nm. Power output was reported in all the studies ranging from 50 milliwatts (mW) to 5000 mW. All the included studies evaluated PEP after root canal therapy, root canal retreatment or surgical endodontics. Out of the five clinical studies, a total of three studies showed comparable PEP outcome between phototherapy and control groups. However, two studies showed statistically significant improvement in PEP in the phototherapy group as compared to the control group. CONCLUSIONS : It remains debatable whether phototherapy reduces PEP after root canal therapy. Further robust RCTs with standard laser parameters are warranted to assess the efficacy of phototherapy in the management of PEP.