The self-field loss of BSCCOrAg tapes has been measured in combination with an external AC magnetic field. This situation occurs when conductors are used in applications such as coils or cables. An increase of the self-field loss due to external AC magnetic field is observed. An increase of the self-field loss caused by a decrease of the critical current is only a minor effect. For magnetic field amplitudes higher than 10 mT, the self-field loss is described reasonably well by the self-field loss and a dynamic resistance contribution calculated from the DC voltage–current relation in AC magnetic field. For magnetic field amplitudes smaller than 10 mT, the dynamic resistance contribution from the DC voltage–current relation only describes a small part of the increased self-field loss.