Biological traces are traces of human, animal and plant origin. Most biological evidences found an a crime scene are of human origin. Biological traces are hair, blood, semen, saliva, sweat, tears. We can distinguish between indisputable samples and disputable traces. Indisputable samples are taken fom suspects, victims and all other persons who may come in contact with traces or objects in the crime scene and are used for exclusion. Disputable traces are traces found at the crime scene, on objects or persons that are connected to the crime scene or commited offense. When taking biological evidence it is necessary to implement anti-contamination measures and measures of self-protection. Blood traces are analyzed in criminal offenses, mostly murder and attempted murder. Blood traces can occur by pouring, dripping and transfer. From the blood we analyze AB0 blood type, MN and Rh factor. Sperm traces are usually analyzed with criminal acts against sexual freedom and sexual morality. Hair analysis is used to connect the perpetrator to the crime scene or the victim. Traces of saliva are used to determine AB0 blood type. DNA analysis uses characteristics of the DNA used to identify the person and determine the origin of biological traces. DNA analysis is used in the analysis of criminal offenses, identification of missing persons and to prove kinship. Whith DNA analysis we can examine traces that contain nucleus. We can distinguish between RFLP analysis, STR-PCR analysis, mitochondrial DNA analysis, sex chromosome profiling and single nucleotide polymorphism.