Two quantitative analysis methods for measuring sulfonamides in spiked meat and blood samples are described. Both methods are based on thermospray tandem mass spectrometry. One method includes on-line liquid chromatographic separation before the tandem mass analysis and the other is based on flow injection. The extraction procedure is a simple method where blood or minced meat is shaken with ethyl acetate. The ethyl acetate phase is isolated and evaporated to dryness. The chromatographically separated sulfonamides are mass analyzed by detection of the characteristic fragment ion, m/z = 156, which all sulfonamides share. The mass analysis of the flow-injected samples is made by parent ion detection. The analysis method for the chromatographically separated compounds has slightly lower detection limits for the sulfonamides compared to the flow injection method. But the detection limits for all compounds are well below the maximum residue limit of 50 ppb in meat. The flow injection method can analyze 40-60 extracts/h and show no contamination or sensitivity problems even after more than 1000 analyses of crude extracts. Both methods provide good sensitivity, some quantitative accuracy, and acceptable detection limits.