Selective timber harvesting in tropical rain forests is becoming increasingly common and plays an important role in integrating economic development needs and conservation goals. Understanding the effects of logging on forest ecosystems can contribute to the design of sustainable management techniques and minimise the negative effects of timber harvesting on wildlife. Despite this, few previous studies have attempted a detailed ecological investigation of the effects of logging on wildlife. Here I present the results of a comparative study carried out in logged and unlogged forest in the Budongo Forest Reserve (January 1993 - September 1994) investigating differences in blue monkey (Cercopithecus mitis stuhlmanni) ecology and habitat composition. The ecology of groups of blue monkeys in logged and unlogged forest was compared and attempts made to relate differences in ecology to differences in habitat composition and food availability. In Budongo, widespread selective felling of 'mahogany' (genus Khaya and Entandrophragma) over the last 60 years has had a considerable impact on the plant and animal communities, resulting in significant changes in vegetation communities and an increase in density of four primate species (Plumptre et al 1994). It is thought that unlogged forest tends towards a low species diversity (monodominant) forest type, with Cynometraa lexandria s the dominant tree species. In addition, logging in Budongo has typically been carried out at a relatively low intensity. These two factors have been important in determining the nature of the changes in vegetation composition and plant phenological patterns subsequent to logging. Noticeable among these differences are a higher tree species diversity and higher proportion of colonising tree species in logged forest relative to unlogged forest. As a result, blue monkeys in Budongo experience greater food availability, occupy smaller home ranges and attain a higher population density in logged forest. There are several considerations which are important when discussing the findings of this study in the context of forest management for timber production. Firstly, the unique nature of the vegetation in Budongo prior to logging, and the type of timber harvesting carried out, both play an important role in determining the response of the vegetation and wildlife communities. Secondly, although logging in Budongo may lead to an increase in the density of blue monkeys and other common generalist/frugivore species, it may have negative effects on other more ecologically specialised taxa. The findings of this study are discussed in the context of understanding the effects of management on the vegetation composition and blue monkey density in the Budongo Forest Reserve. The results support the observation that the effects of logging are complex and in some cases can even be beneficial to wildlife. Forest management should take into account prior knowledge of forest types and the likely response of wildlife communities. If tropical foresters are to satisfy economic development requirements and meet conservation goals then management must be applied with care and after some consideration of the potential effects on the ecosystem.