Critical values are the values that may lead to patient’s harm or death. This subject has been discussed by scientific community in many countries of the world for a long time. The first one who implemented this term (initially it was «panic values») was G.D. Lundberg (1972). Since that time the usage of critical values is widely discussed in the laboratory society: from that time, the interest on this problem is growing and the term «critical values» begins to exist. However, since the introduction of the document CLIA’88, involving work with critical values, to date the question remains about the list of analytes and the specific values. Official organisations made guidelines on choosing critical values, ways of delivery of the results to clinicians, and of alarm lists which can be used as drafts by laboratories to finish their own alarm lists because of contingents. In spite of that there is a tendency of the values inside countries one can see difference in term using (for example in Europe there are only three common analytes: potassium, sodium, glucose). Now the common thing in literature is an advice to analyze and estimate of data in hospitals and to know the difference between the different terms of critical values (e.g. alert values). To develop the most relevant ones requires close cooperation between clinicians and laboratory. The aim of this review is to highlight the problem of critical values determing in world practice: list of analytes, their values, conducted studies and surveys. The aspects of designing of critical values transfer protocols and compliance with them are not highlighted in this review as this question is widely discussed since ISO 15189 output.