The effects of staurosporine, a potent protein kinase C inhibitor, and okadaic acid, a non-TPA tumour promoter, on the adhesion of BHK fibroblast were investigated. Staurosporine at 2.5 and 5 microM was found to stimulate a gradual increase in BHK cell adhesion as well as spreading in 3% serum-containing medium. An increase of approximately 27% over the control value was found at 5 microM concentration in 20 minutes. No such effect was seen in serum-free conditions. Staurosporine at 5 microM, enhanced BHK cell-cell adhesion in 3% serum and in serum-free conditions. Okadaic acid, a phosphatase inhibitor, at concentrations between 0.25 and 1 microgram/ml, was found to inhibit BHK cell-substratum adhesion and spreading. The inhibitory effect was time and concentration dependent. These findings suggest that protein kinase C might be involved in the mechanism(s) controlling BHK cell attachment.