We evaluated the use of two tumour markers Cyfra 21.1 and tissue polypeptide antigen (TPA) for disease monitoring. Assessment of response to WHO criteria was compared to response assessment according to changes in the tumour marker levels. The criteria defined for marker response were a 65% decrease for a partial response and a 40% increase for progressive disease. When response evaluations with a positive lead time were included, 72% of 115 evaluations for Cyfra 21.1 and 59% of 107 evaluations for TPA yielded the same result. Most discordant evaluations were caused by those evaluations whereby the patient achieved a partial response according to the WHO criteria and had normalisation of the marker. Less cases with a positive lead time, more negative lead times, and more patients with progressive disease without an increase of the marker were seen with TPA compared to Cyfra 21.1. In conclusion, Cyfra 21.1 follows the changes in the tumour load better than TPA. Rising levels of both markers nearly always indicate disease progression, and such knowledge easily obtained may prevent the continuation of ineffective treatment.