INTRODUCTION: Drug discrimination is an important technique in behavioral pharmacology since the last 40 years. LSD affects multiple receptor subtypes of the serotonergic system and is one of the most powerful agents producing psychedelic effects. METHOD(S): Male Sprague Dawley rats were trained in two lever operant conditioning chambers using the FR10 schedule of reinforcement to discriminate 0.08 mg/kg LSD from vehicle, 15 min following administration. The experiment was conducted 5 days/week during the light phase of the light/dark cycle. AIM(S): The aim was to examine the time after which the animals were able to discriminate two treatment conditions. Animals were tested 5, 15, 30, and 90 min after 0.08 mg/kg of LSD administration. RESULTS: All animals tested 15 min following LSD administration choose the LSD lever. In the test carried out after 5 min following injection, 70% of rats choose the LSD lever. The subjects tested after 30 min displayed similar discrimination as tested following 15 min. However, after 90 min following LSD administration, the rats choose the vehicle lever. CONCLUSIONS: The present data suggest that the cue produced by LSD in the drug discrimination test could be detected shortly after its administration.