Aims. To establish whether there is a relationship between tobacco industry support of basic research and the conclusions drawn by the authors of that research. Design. A sample of 91 papers investigating the effects of tobacco or nicotine use upon cognitive performance was analyzed to see if the pattern of conclusions drawn by researchers acknowledging tobacco industry support differed from the pattern of conclusions drawn by researchers not acknowledging tobacco industry support. Findings. Scientists acknowledging tobacco industry support reported typically that nicotine or smoking improved cognitive performance while researchers not reporting the financial support of the tobacco industry were more nearly split on their conclusions. Conclusions. While it is only possible to speculate on the possible reasons, the existence of a possible bias in the published literature according to funding source must be given serious consideration.