Hesperetin　(HST),　a　natural　flavonoid,　has　potent　antitumor　effects　on　lung　adenocarcinoma;　however,　its　effects　on　lung　squamous　cell　carcinoma　(LUSC)　are　currently　unknown.　The　present　study　aimed　to　investigate　the　anticancer　effects　of　HST　on　LUSC　cells.　The　influence　of　37.5,　75　and　150　mu　M　HST　on　the　H1703　cell　line,　and　of　75,　150　and　300　mu　M　HST　on　the　H226　cell　line　was　determined　using　the　Cell　Counting　Kit-8　method,　cell　cycle　assay,　JC-1　mitochondrial　membrane　potential　assay　and　Annexin　V-FITC/PI　staining.　DMSO-treated　cells　were　used　as　the　control　group.　Western　blotting　was　performed　to　detect　the　protein　expression　levels　of　cyclin　B1,　CDK1,　Bcl-2,　Bax,　caspase-3,　cleaved　caspase-3,　phosphorylated-eIF2　alpha,　eIF2　alpha,　glucose-regulated　protein　78,　CHOP,　Notch1　and　Hes-1.　The　relationship　between　endoplasmic　reticulum　stress　(ERS),　Notch1　signaling　and　apoptosis　was　examined　using　the　ERS-inhibitor　4-phenylbutyric　acid　(4-PBA;　500　mu　M)　and　the　Notch1　signaling　activator　Jagged-1　(4　mu　M).　In　vivo,　mice　were　divided　into　control,　HST　(30,　60　and　90　mg/kg/q2d)　and　cisplatin　(2　mg/kg/q2d)　groups　to　evaluate　the　anti-LUSC　effects　of　HST.　The　results　revealed　that　HST　inhibited　the　viability　of　H226　and　H1703　cells,　leading　to　cell　cycle　arrest　at　the　G(2)/M　phase　and　the　induction　of　cell　apoptosis.　In　addition,　HST　downregulated　the　Notch1　signaling　pathway　and　increased　ERS.　In　H1703　cells,　4-PBA　and　Jagged-1　reduced　the　expression　of　apoptosis-related　proteins,　and　Jagged-1　also　reduced　the　expression　of　ERS-related　proteins.　In　vivo,　HST　reduced　tumor　growth　without　any　apparent　toxic　side　effects.　In　conclusion,　HST　may　exert　its　antitumor　effects　by　inducing　G(2)/M　cell　cycle　arrest　and　inhibiting　the　Notch1　signaling　pathway　to　activate　ERS-induced　apoptosis,　making　it　a　promising　agent　for　treating　LUSC.