Welds in high strength steel have been studied experimentally and results from two test series are reported. One series concerned butt welds with undermatching electrodes with the purpose of investigating the strength and ductility. The conclusion is that moderately undermatching can be used maintaining a sufficient ductility. The other test series concerned filler weld with the purpose of developing a design formula covering undermatching as well as overmatching electrodes. Such a formula is proposed using results from the new tests as well as tests reported in literature.