Summary The use of forming limit diagrams (F.L.D.), drawn for rectilinear strain-paths, can not allow to predict the success of a drawing operation in press-shop, because the industrial blanks usually show complex strain-paths. The aim of this study is to predict the strain path influence on the F.L.D., from the limit stress curve. We consider two types of paths, composed of two straight segments corresponding to stretching-tension and tension-stretching sequences. The calculated results are checked by experimentals ones, obtained with isotropic copper sheet. Then, we compare this method to the one using iso-strain ellipsis. The equivalence of these methods being suggested in a general case, we have verifyed they give the same results, for the sequences considered here. So, we can state that the isostrain ellipsis method contains the same assumption than the single limit stress diagram. This last method allows to predict very easily the onset of necking for any non straight strain path.