5-Hydroxyindoleacetic acid (5HIAA), a metabolite of serotonin is utilized clinically to detect the carcinoid tumors. A simple method for determination of 5HIAA in urine, serum, and cerebrospinal fluid (CSF) is described. For quantitation in urine, the method is based on a single step extraction followed by separation on an anion exchange short column. This type of column enabled the direct injection of the organic solvent on the column without any interference in the spectra or symmetry of the peak. For serum and (CSF) analysis acetonitrile deproteinization was used with injection on the same column. 5HIAA was detected by its native fluorescence which was more sensitive and more suited for daily routine analysis compared to the more common electrochemical detection. Reference range for 5HIAA in different human fluids is determined. Patients with carcinoid syndrome showed elevated levels of 5HIAA in both urine and serum.