The photoneutron reaction 181 Ta(γ, 3n) 178m,g Ta was investigated with the beam from the NSC KIPT electron linear accelerator LUE-40. The measurements were performed using the residual γ-activity method. The bremsstrahlung flux-averaged cross-sections σ(E γmax ) , σ(E γmax ) m , σ(E γmax ) g and the isomeric ratio of the reaction products d(E γmax ) have been measured. Theoretical values of averaged cross-sections and isomeric ratio were calculated using partial cross-sections from the TALYS1.95 code for different level density models LD 1-6. The obtained experimental d(E γmax ) agree with the literature data, but differ from the theoretical values in absolute magnitude and the behavior of the energy dependence. A comparison of the found averaged crosssections with the calculated ones showed the best agreement for the case of the LD 5 model.