The frequency of defective coffee beans was determined in samples of unripe fruits of the cultivar Mundo Novo (Coffea arabica).Ten samples of 1000 seeds each obtained from green fruits after sundrying and shelling were independently scored for the commercial defects by three coffee classifiers. Each one of the classifiers recorded the occurrence of green-coated, brown and black beans before and after removal of the silver skin. The data revealed that more than half of the beans had normal green color whereas 44.9 per cent were green-coated, 3.5 per cent were brown and 0.1 per cent were black beans. The removal of the silver skin affected the previous classification giving 59.7 per cent of normal green beans, 39.5 per cent of brown and 0.3 per cent of black beans. These observations indicated that the so-called green-coated beans are caused by the presence of the silver skin which retains green pigments probably chlorophyll. On the other hand the browns which have been considered as product of over-fermentation were scored in a much higher frequency whereas the percentage of black beans was little altered after the removal of the silver skin. The factors responsible for origin of the brown and black beans are discussed. Preliminary studies of the cup quality of the normal green beans selected from these samples indicated that the quality of the beverage had the poor taste characteristic of unripe coffee despite of the appearance of the beans.