The article presents the results of tests concerning the mechanical and structural properties of single-spot and twin-spot laser beam welded joints made of a steel strip, the chemical composition of which corresponds to that of steel 0H15N7M2J. In addition, the article presents the comparison concerning the geometry of joints made using the single and twin-spot laser beam. The test joints were subjected to heat treatment involving austenitisation, cold treatment and ageing. The study also involved the comparison of the mechanical and structural properties of the joints subjected and those not subjected to the above named heat treatment.