Sixteen Thiès strain rabbits were used to study the effect of the calcium/phosphorus ratio on plasma calcium, inorganic phosphorus and magnesium levels during pregnancy. Animals were allocated in 2 groups of 8: one receiving a diet with a Ca/P ratio of 1:0 and the other a diet with Ca/P ratio of 2:1. Water was given ad libitum for all rabbits. Results obtained showed that Ca blood level was significantly higher in rabbits receiving the diet with Ca/P ratio of 2:1 before covering and during the first week of pregnancy. During the last 15 d of pregnancy, Ca blood level decreased significantly in the 2 groups of animals. Plasma inorganic phosphorus and magnesium levels were not significantly different in the 2 groups of rabbits until the 2nd wk of pregnancy. But at the end of pregnancy, while phosphatemia and magnesemia decreased in rabbits fed a high Ca/P ratio, in the other group these parameters remained unchanged.