The influence of tris(4-chlorophenyl)methanol (TCPM) and dichlorodiphenyltrichloroethane ( o,p′DDT) on forskolin induced cAMP signalling in single adherent bovine oviductal cells was investigated. An increase in the intracellular cAMP levels was measured indirectly by an increase in the 520/580 nm fluorescence emission ratio of the protein kinase A fluorosensor (FICRhR). FICRhR was microinjected into single cells, and the 520/580 nm fluorescence emission ratio was monitored by image cytometry with an image analysis system as a measure of intracellular cAMP concentration ([cAMP] i). Applications of dibutyryl cAMP and forskolin caused time- and dose-dependent effects on [cAMP] i in single oviductal cells. The addition of 16 or 32 μ m TCPM or DDT for 1 h to the culture medium decreased the intracellular cAMP concentration significantly, whereas 8 μ m was not able to influence the [cAMP] i. In the presence of both pesticides at 16 μ m the forskolin (30 μ m)-induced [cAMP] i was significantly reduced after 1 h of incubation. It is suggested that TCPM can have the same influence compared with DDT on cells responsible for reproduction.