Citalopram, a selective serotonin reuptake inhibitor, is used as an antidepressant agent. In this studyan on-line solid phaseextraction methodwith spectrofluorometric detection was developed. Solid phase extraction cartridges contain 200 mg C18 with a particle size of 45 mu m. The best solvent system found was consistend of ethanol and 0. 1 M acetic acid (40:60, v/v) for elution. The optimized values of injection volume and flow rate were 1 mL and 2.5 mL min(-1). The excitation and emission wavelengths were 240 and 300 nm. The calibrations were linear in the concentration range of 1.0 x 10(-7)-1.5 x 10(-6) M in aqueous solution and 2.5 x 10(-7)- 1.2 x 10(-6) Min serum. The limit of detection values were 1.6 x 10(-8) M for citalopram in tablets and 1.7 x 10(-8) M in serum samples. The limit of quantification values were 5.2 x 10(-8) M for citalopram in tablets and 5.5 x 10(-8) M in serum. The proposed method has been applied successfully for the determination of citalopram HBr in pharmaceutical tablets and also in spiked human serum. The recovery values of the method were 99.5-100.6% for tablets and 98.8-100.9% for serum.