This work owes its importance to the fact that it aims at knowing and measuring the concentrations of alpha-particles emitters discrete by the human body in the urine in particular. Knowledge of these concentrations is extremely important since it reveals whether a person has received such doses of radioactive materials emitting alpha-particles that result in the occurrence of malignant tumor and mutations. This subject being so ssential to the health of individuals and being a great help to physicians to make the proper diagnosis in the relevant cases, has imposed itself on us as the topic of this thesis.Human urine samples were taken from Iraqi workers in different fields (phosphate plants, fertilizer plants, teaching staff in nuclear physics laboratory, painters, patient and reference healthy people of different ages), using PM-355 solid state nuclear track detectors. The exposure method was used by immersing PM-355 detectors in urine samples for three weeks, then etching by 6.25N NaOH for 5 hrs. The track density was measured via an optical microscope. The alpha emitters concentrations in the urine samples were calculated in comparison with standard samples that were prepared in the nuclear laboratory of physics department- College of Science AL-Nahrain University.The obtained results show that the concentrations of alpha emitters in the urine samples of patients range from 1.81ppm to 2.87ppm , from 0.087ppm to 1.32ppm in reference healthy people, in painters from 0.77ppm to 1.46ppm,workers in phosphate plants from 0.94 ppm to 1.89 ppm, workers in fertilizer plants from 1.0ppm to1.42 ppm , and from 1.0 ppm to 1.29 ppm in teaching staff in nuclear physics laboratory .Deductions from the results of this work regarding the dependence of concentrations on the person's occupation, years of service, sex, age and health condition have been dealt with in sufficient details as required.