Spatial and temporal constraints determine multisensory integration (e.g. Macaluso & Driver 2005, Driver & Noesselt, 2008). Recent neuroimaging studies investigated the neural basis of audiovisual interactions in perception (e.g. Noesselt et al. 2007, Bonath & Noesselt et al. 2007) but none of these have directly compared temporal with spatial factors using fMRI. Moreover, attention to either the spatial or temporal domain may further modulate the neural underpinnings of audiovisual processing. In the present fMRI-study, we varied both spatial and temporal properties of audiovisual stimuli, while subjects performed either a temporal or spatial audiovisual discrimination task. Sounds were presented at two different spatial positions (left/right) with both simultaneous and non-simultaneous light flashes (SOA 300 ms). These sound/light combinations occurred either within the same hemifield (sound/vision left/right) or at opposite hemifields (sound left/vision right and sound right/vision left). Preliminary results revealed modulations within non-specific thalamic nuclei that were differentially modulated by task demands (attention to spatial/temporal stimulus properties). Our results are in line with recent theories on multisensory interplay in the thalamus (Schroeder & Foxe 2005) and their implications will be discussed.