The method for lung cancer detection by optical analysis of body fluids relates to analyzing samples of blood, urine and sputum by fluorescence spectroscopy in order to detect the presence of naturally occurring molecules in the fluids that serve as biomarkers indicative of cancer in the human body. The analysis can be carried out based on fluorescence emission spectra, fluorescence excitation spectra and synchronous (emission and excitation) spectra of bio-samples. The early detection and diagnosis of lung cancer may be made by comparison of ratios of fluorescence emissions and/or excitation intensities of tryptophan, tyrosine, elastin, collagen, bile pigments, NADPH, flavins and various species of porphyrins.