A portable Fourier transform infrared (FT-IR) multicomponent point-of-care analyzer was tested for the diagnosis of methanol intoxications. Breath analysis with FT-IR was fast and easy, and no sample preparation was needed. The analyzer was adequately sensitive and accurate in detecting and quantitating clinically relevant amounts of ethanol and methanol in the breath of seriously ill patients. FT-IR spectrometry was also suitable for nearly on-line monitoring of the exhaled ethanol and methanol during hemodialysis. The breath analysis results correlated well with blood samples. The FT-IR method used also has a traceable calibration to physical properties of the analyte, and the measured spectra can be saved for later analysis.