Today, some kind of laboratory results is required for around 70% of the diagnostics and follow-ups for diseases. In many of the cases the time from sampling to a result is very critical. Therefore the discussion of how to improve this situation has begun. For many analyses serum has been the routine choice for a long time but now it is disputed. After blood collection in a serum tube it is essential to wait 30-60 minutes before centrifugation and analysis of the sample, a long time for someone in an acute state. Other problems like post centrifugation clots of fibrin causing false results or time-consuming reruns of the sample have also been reported. These problems have initiated the laboratory in Hudiksvall’s hospital to find out an alternative to the common serum sampling.In this report, the differences between serum and lithium heparin plasma for 31 analyses has been evaluated. Paired blood samples, one serum and one plasma, were collected for routine, hormonal and for tumor markers analyses and analyzed in a Cobas c501, e411 or e601 (ROCHE). The results of the analyzed samples were compared to each other by statistical analysis.The results prove that serum and lithium heparin plasma is equal for ALT, GGT, NT-proBNP, FT3, FT4, cobalamin, LH, prolactin, TSH, CA19-9, CEA and PSA. The results also prove that serum and lithium heparin plasma is not equal for 19 other analyses. Therefore, a shift between different types of sampling is not to be recommended without further evaluations.