We have determined the levels of complement C3, C4 and immunoglobulin G, M, A in mothers’ and cord blood serum. Parallelly properdin factor B and immunoglobulin G tests were done in urine samples. All estimations were performed on Immunochemistry Analyzer “Beckman”. The investigations were made on 30 healthy pregnant women and 30 with arterial hypertension at the end of third trimester. In the mothers’ serum C3 was not significantly changed. In the cord blood of healthy pregnant women it was 0.69 g/L. (SD 0.12) and in those with hypertension 0.38 g/L. (SD 0.15), which means significantly decreased. Complements C4 was not significantly increased in mothers’ and cord blood serum. Properdin factor B was significantly increased in mothers' and cord blood serum (healthy pregnant women in serum 0.38 g/L., SD 0.07; with hypertension 0.48 g/L., SD 0.15; while in the cord blood serum of healthy women it was 0.14 g/L., SD 0.06; and hypertensive it was 0.22 g/L., SD 0.10). The same parameter was significantly decreased in the urine of healthy subjects 3.94 mg/L., SD 1.91; and in the hypertensive too, 2.42 mg/L., SD 0.90. The IgG level was significantly increased in the urine of healthy pregnant women 4.42 mg/L., SD 2.24; with hypertension 6.64 mg/L., SD 3.61. IgM was not significantly changed in mothers' and cord blood serum. IgA was significantly increased in the cord blood serum of healthy mothers', 0.02 g/L., SD 0.01, with hypertension 0.12 g/L., SD 0.05.