Fatigue　tests　were　carried　out　on　tensile-shear　spot-welded　specimens　under　random　loading;　at　the　same　time,　natural　frequencies　at　different　life　stages　were　measured.　Test　results　were　compared　with　that　under　constant　amplitude　loading.　The　relationship　between　damage　and　natural　frequency　change　ratio　established　under　constant　amplitude　loading　is　here　modified.　The　nonlinear　damage　evolution　equation　was　established　using　the　damage　represented　by　frequency　change　for　spot　welds.　The　fatigue　life　of　spot　welds　under　random　loading　was　predicted　with　this　damage　evolution　relationship　using　the　rainflow　counting　method　results,　as　well　as　other　life　prediction　methods　with　different　counting　methods.　Comparison　of　life　prediction　results　showed　that　the　method　using　changes　of　natural　frequency　can　be　an　on-line　approach　and　the　predicted　lives　have　a　good　agreement　with　the　experimental　data.　(C)　2008　Elsevier　Ltd.　All　rights　reserved.