Pemetrexed is approved to treat non-small cell lung cancer and has an overall favorable toxicity profile. We describe a 58-year-old man who developped an anaphylactic shock within few minutes from the beginning of pemetrexed perfusion. Pemetrexed was discontinued and the patient's symptoms gradually resolved with administration of symptomatic treatment. Serum tryptase level remained normal and intra dermal skin tests were negative eventhough a nonspecific papule was noted. This case suggests that caution should be exercised when prescribing pemetrexed and clinicians must be warranted for the possibility of serious adverse events associated with pemetrexed use.