Rats received NMDA lesions of the bed nucleus of the stria terminalis (BNST) and then ten aversive conditioning trials in which exposure to a context was paired with footshock. For half the animals, shock was presented one minute after the onset of each context exposure; for the other half, shock was presented after 10 minutes. With the one-min context duration, aversive conditioning (measured by freezing) was unaffected by BNST lesion. In contrast, at the 10-min duration, lesioned animals froze substantially less than sham controls. When one-minute-conditioned animals were left in the context for 10 minutes, freezing that was evident (though declining) throughout the test was not affected by the BNST lesion. When freezing over 10 mins was similarly examined in the 10-min-conditioned animals, BNST lesions caused a deficit that was consistently evident over time. The results indicate that the BNST is involved in aversive conditioning to long-duration, but not merely contextual, conditional stimuli. Results may be less consistent with the view that BNST becomes activated after prolonged fear than the view that it is involved when a cue’s onset has a remote temporal relation to shock.