Background:　Homologous　recombination　deficiency　(HRD)　is　a　predictive　factor　in　ovarian　cancer,　breast　cancer,　and　prostate　cancer　for　Poly　(ADP-ribose)　polymerase　inhibitors　(PARPi)　therapy.　HRD　is　understudied　in　head　and　neck　squamous　cell　carcinoma　(HNSCC)　and　the　impact　of　HRD　on　prognosis　and　the　tumor　immune　microenvironment　is　unclear.　Methods:　We　studies　eight　head　and　neck　cancer　patients　in　our　center　and　compared　the　HRD　score　for　each　HNSCC　patient　in　The　Cancer　Genome　Atlas　(TCGA)　cohort　with　corresponding　clinical　characteristic　mRNA　and　mutation　data.　Results:　Results　indicated　that　the　clinical　stage　(P　=　0.016),　gender　(P　=　0.003),　clinical　T　stage　(P　＜　0.001),　HPV　16　(P　=　0.003),　pathologic　T　stage　(P　=　0.002),　and　lymphovascular　invasion　(P　=　0.004)　were　associated　with　a　homologous　recombination　deficiency　high　score　(HRD-H)　by　logistic　analysis.　Multivariate　analysis　showed　that　HRD-H　was　an　independent　factor　predicting　survival　with　the　adjustment　of　age,　gender,　clinical　T　stage,　clinical　N　stage,　and　clinical　M　stage　(HR　95　%CI　1.517;　1.128-2.039,　P　=　0.006).　The　proportion　of　tumor　mutation　burden-high　(TMB-H)　and　microsatellite　instability-high　(MSI-H)　patients　in　HRD-H　patients　are　relatively　low　(9.97%　and　0.0%　respectively).　A　non-inflamed　tumor　microenvironment　was　also　found　in　HRDH　patients.　In　our　center,　we　found　that　two　HRD-L　HNSCC　patients　presented　with　an　inflamed　tumor　microenvironment　and　had　a　good　response　to　PD-1　therapy.　Interestingly,　the　higher　HRD　score　was　31　and　was　a　non-responder　to　ICI　treatment.　Conclusions:　HRD-H　is　associated　with　poor　outcome　in　HNSCC　patients.　Those　patients　may　benefit　from　PARPi　treatment　rather　than　ICIs　treatment　for　its　non-inflamed　tumor　microenvironment.