The presentation of understandable and stimulating lectures on difficult scientific and medical issues is in our opinion an art in decline. This disconcerting trend has, however, received little attention. In this essay, we expose the most common fallacies and pitfalls encountered in poor lectures, discuss the underlying reasons why they occur and consider some remedies to improve the situation. The status of oral communication should in our opinion be upgraded. To give a first rate, lucid lecture is an important service to the scientific community and should be recognised as such. When principal speakers at symposia are selected, and when researchers are considered for academic positions, documented proficiency in oral communication should be given more weight than is currently the case. This essay does not purport to be a treatise on rhetoric. We believe that a more efficient approach is to focus attention on the common blunders. This we have done in a provocative manner to invite comments and discussion.