Neonatal calves in good farm practice systems are subject to constant monitoring, and as a part of “passive immunity transfer monitoring” a sample of their blood is taken during the first 5 days of their life. Apart from the total protein (TP) the remaining blood profile parameters are not adequately analyzed. Recent research has confirmed the existence of differences in normal blood parameters between different breeds and age categories of the same species. The objective of our study is to determine “de novo” hematology and biochemistry reference intervals for Simmental neonatal calves up to five days of age, so that more information may be extrapolated from every blood sample taken. In comparison with published data in our research we found a high upper limit for TP and extremely low upper limit for BHB, as for GGT we found the highest upper limit ever reported, to the best of our knowledge. Comparing our results with the results of similar research we found differences between our RI and published RI for similarly aged calves of different breeds. High levels of TP and GGT in calf serum are indicators of successful colostral immunity transfer. According to consensus recommendations for passive immunity transfer, the calves from our study belong in the “excellent transfer group”, and that status is even further confirmed by high GGT levels. We believe that the low concentrations of BHB found in our calves is an indicator of a high level of animal welfare, a result of good farm practice related to the care and handling of neonatal calves. The RI found in our research can be used for interpretation of hematology and biochemistry parameters in neonatal Simmental calves raised in free-range cow-calf operations.