The bcl-1 locus on chromosome 11 at band q13 has been shown to be rearranged in some chronic B lymphoid malignancies with the t(11;14)(q13;q32). Chromosome 11 abnormalities occur in solid tumors including squamous cell cancers and adenocarcinomas. We have recently reported the frequency amplification of the bcl-1 locus in squamous cell carcinomas of head and neck origin, and increased copy number also has been found in some breast adenocarcinomas. In this investigation, we analyzed the arrangement, copy number and expression of this locus in 111 primary non-small cell lung cancers. Bcl-1 was found to be amplified three- to 10-fold in seven fresh tumors. Whereas none of 51 adenocarcinomas showed bcl-1 amplification, six of 46 squamous cell carcinomas revealed an increase in bcl-1 copy number. This amplification was more frequently associated with larger and more poorly differentiated tumors. None of the cancers showed rearrangement of this locus.