The objective of the present study was to investigate effects of feeding pregnant ewes with a reduced-energy diet during the late gestation period by monitoring changes in blood levels of some biochemical parameters. A total of 30 5-6-year-old Chios ewes (20 pregnant, 10 non-pregnant) were used. On day 105 of their gestation the pregnant ewes were divided into 2 treatment groups of 10 animals in each: an energy restricted group (ER) and normal energy group (NE). The ewes that were not pregnant were assigned as a group of non-pregnant ewes (NP). Blood samples were taken from the ewes of all groups on days 120, 127, 134, 141, and 148 of gestation and analysed in order to determine levels of total protein, albumin, globulin, albumin/globulin (A/G) ratio, glucose, and total lipids. The results indicated that the levels of total proteins and globulin were found to be lower in the last 4 weeks of gestation in ER and NE groups as compared to those in the NP group. Levels of total protein and globulin in NE and ER groups persistently decreased between days 120 and 148 (P < 0.05). During the last 4 weeks of gestation glucose levels of pregnant ewes were found to be significantly lower (P < 0.05) as compared to those of NP ewes. No difference was discovered between NE and ER groups in the levels of total protein, albumin, globulin, glucose and A/G rations. Levels of total lipids constantly increased in the last 5 weeks of gestation. The highest increase in total lipids was seen in the ER group ewes (P < 0.05). These findings indicate that feeding with a reduced energy diet may not adversely affect maternal immunity and transfer of Igs to colostrum. However, significant increases in total lipids in the ER group indicate that increased energy needed for fast fetal growth was met by the mobilisation of reserve fats.