Biochemical blood parameters generally show fluctuations during the day. The aim of this study is to determine the variations of the following parameters: hemoglobin, glucose, triglycerides, ASAT, ALAT, urea and creatinine in New Zealand white (NZW) rabbits, kept under five different circadian rhythms (12/12, 14/10, 10/14, 16/8, 8/16, light/dark). These parameters were analyzed by using a reflection photometer (Reflotron). Most results are found within the physiological range for this species but there are significant differences among cycles. These findings could be explained by the dependence of the biochemical blood parameters on the light/dark cycle. It can be concluded that the most useful cycle to find fewer variations of the biochemical blood parameters in NZW rabbit is 12/12 light/dark cycle.