To evaluate the pronostic value of an elevated seric carcinoembryonic antigen (CEA > 10 ng/ml) at diagnosis, in patients with lung cancer, a pair study was done: couples of patients with same staging and histologic type were established, one patient with high CEA level compared to one patient with normal CEA level (< 5.5 ng/ml). Other markers were measured: neuron specific enolase (NSE), squamous cell carcinoma (SCC) or Cyfra 21-1. Survival was the end point of comparison. For 89 couples created, patients with low CEA level had a better survival rate at one year ( p = 0.02), this prognosis advantage was confirmed by a comparison of survival curves with Mantel-Cox and Breslow test (p = 0.01), but not by the signs test. These differences were also observed for the 71 couples of squamous cell carcinomas and adenocarcinomas, and the apparied signs test was still not significant. The poor prognosis persisted for patients with high CEA level, when one another marker's level (NSE or SCC or Cyfra 21-1) was increased, in comparison with patients with any marker increased. On 29 couples of all histological subtypes or on the 25 couples of non small cell lung cancer, the signs test and the comparison of survival curves were significant, but not the 1 year survival rate. This study shows that a CEA level greater than 10 ng/ml at diagnosis is a poor pronostic factor in patients with lung carcinoma, independent of the stage of disease and of the histologic type.