A gas chromatographic method using a heated direct glass injection port for quantitative microanalysis of cyclopropane in whole blood is described. Evaluation of the method revealed that the direct injection technique is applicable to rapid and accurate analysis of cyclopropane concentrations in blood samples of small volume (10 [mu]l). Quantitative recovery of cyclopropane from blood was evaluated by determination of the blood/gas distribution coefficient of cyclopropane in blood of varying hemoglobin concentrations and temperatures. The characteristics of hydrogen flame ionization detectors for analysis of the anesthetic agent are discussed.