In 1993, Great Spotted Woodpeckers were studied in the forestry of Odoorn (1730 ha)(Table I, Fig. 1). Territories were mapped and once a nest was found, its content was examined with the aid of a mirror and a maglight. Eggs were counted and the age of nestlings was estimated. Some parameters of the nest site were quantified (Figs. 1-4). In the study area 160 territories were mapped in which 46 nests were found (fig. 1). Great Spotted Woodpeckers preferred nesting in broad-leaved trees. Given their scarcity, a preference for excavating holes in dead trees was found (Table 2). Laying of the first egg in 43 nests varied from April 24 to May 15 (mean May 2, SD=5.2). One repeat-clutch was started on May 25; in this case, the first clutch was started on May 6. Clutch size in 22 nests ranged from four to seven eggs (mean 5,7, SD=0.89). Clutch size declined in the course of the breeding season (Fig. 6). Breeding success was high. The chance that a cluch produced hatchlings was 82%. Once they had young, all pairs succeeded in fledging them. A total of three nests failed, two of which were depredated. Both nests were excavated in slender (girth at nest height 50 cm), dead trees. Predators had forced a hole in the side of the nest, right through the wall.