An analytical procedure was developed for the determination of the total amount of sterols in the red alga Asparagopsis armata, globally determined as cholesterol, which is the major sterol contained in red algae. Samples, previously saponified with KOH were preconcentrated on DSC-18 solid phase cartridges (SPE) and eluted with dichloromethane stabilized with beta-amylene. Fourier transform infrared (FTIR) spectrometry was employed for selective detection at 1049cm(-1) with a baseline established between 1000 and 1079cm(-1). The results were compared to those obtained by high performance liquid chromatography (HPLC). The concentration obtained in actual samples from alga was 3.37% (w/w) by FTIR and 3.30% (w/w) by HPLC, showing a good comparability between the two methods.