Selfed seeds of cv. Bourbon Vermelho (Coffea arabica) from generations S4 and S5 and also of pure lines obtained from doubled haploids were exposed to X-rays in doses from 5,000 to 23,000 R. A recessive mutation of angustifolia type was found in a progeny of generation M2 derived from the treatment with 12,500 R. Phenotypically normal plants from seeds irradiated with 5,000 and 23,000 R were transplanted to the field and the yields were recorded for fourteen years. Large differences were observed in total yield of individual plants. During seven years, progenies of high and low yielding plants were studied and the data revealed no correlation between the yield of the parental plants and their progenies. In another experiment, the yields were followed for five years, and again, no correlation was found. These experiments indicated that no favorable mutation affecting yield occurred. Since the number of plants analysed was relatively small, the fact that some known morphological mutations were observed, suggest that radiation could be used for increasing genetic variability of C. arabica.