Only recently has the special bereavement associated with the loss of a twin been generally recognised. With the notable exception of Joan Woodward, few have written on the subject. We, therefore, offer a shortened version of a paper written nearly 30 years ago. George Engel was himself a lone twin as well as being an eminent psychiatrist and psychoanalyst in the United States. The length of the paper precludes reprinting the totality but we hope readers will be encouraged to seek out the original published in The International Journal of Psycho-analysis in 1975, Vol 56 part 1, 23–40 .