Sm-doped ZnO (ZnO:Sm) thin films with c-axis oriented wurzite structure were grown by sputtering-assisted metalorganic chemical vapor deposition (SA-MOCVD). In the photoluminescence (PL) measurements of annealed ZnO:Sm, sharp emission lines from intra-4f transitions in Sm3+ ions were observed at room temperature under the excitation energy above the bandgap energy of ZnO (indirect excitation). In the dependence of PL intensity at 77K on Sm concentration, the Sm3+ PL intensity was the largest at Sm concentration of 0.4%. In time-resolved PL measurements, the lifetime of Sm3+ PL became short at higher Sm concentration than 0.4%. These results revealed that a quenching of the Sm3+ PL from ZnO:Sm was induced at higher Sm concentration than 0.4%.