Fragmentation of natural habitats is considered one of the greatest threats to the maintenance of global biodiversity. In this study, we tested the importance of forest patch size and vegetation structure on the richness, diversity, abundance, and composition of the orb-weaving spider guild in an area of the Atlantic Forest (State of São Paulo, Brazil). We sampled 16 sites, grouped into the following categories composed of four sites each: continuous mature forest, continuous secondary forest, large (52–175 ha) secondary forest fragments, and small secondary forest fragments (14–28 ha). The richness ranged from 29 to 55 species per site, but was unrelated to forest size or vegetation structure. The communities from the continuous mature forests were more abundant and less diverse than those from the other categories, but this was due to a few dominant species. The changes in composition were related to the vegetation structure, suggesting that this variable is more important to the composition of orb-weaving communities than the size of the forest patch. Overall, the results indicate that the orb-weaving spider community in this region, even in the fragments, is still rich and diverse, which may be attributable to some characteristics of spiders, such as generalist behaviour and a good dispersal capacity. Nonetheless, our results also highlight the importance of continuous areas, especially those with mature vegetation that harbor a characteristic orb-weaving community that can serve as a source for the fragments.