We have studied laminin and fibronectin expression in a collection of rat cerebellar neural cell lines transformed with a mutant of Rous sarcoma virus which is temperature sensitive for transformation. We show that regardless of their neuronal or glial properties the cell lines produce both laminin and fibronectin. Laminin is expressed in similar amounts in cell lines grown at either the permissive or nonpermissive temperature for transformation, while fibronectin is generally expressed at higher levels in cells kept at the nonpermissive temperature. To provide further evidence that neural cells can produce laminin and fibronectin, double label immunofluorescence studies were conducted on primary cerebellar cultures. Both laminin and fibronectin were found to be present in the primary culture, and laminin was found to be associated with a subpopulation of astrocytes.