In order to assess the lung maturity of the fetus, a biochemical analysis using two reliable, simple and rapid methods (FLM-TDX Abbott and determination of phosphatidylglycerol (PG) have been carried out on 166 amniotic fluids taken by amniocentesis. The patients were particularly pregnant women presenting disorders such as diabetes (n = 41), premature rupture of the membranes (n = 30), hypertension (n = 20), intra uterine growth retardation (n = 13) and gemellar pregnancies (n = 27). The lung maturity of the fetus has been considered as mature (no risk of any hyaline membrane disease: HMD) when the phospholipid rate is higher than 50 mg/g albumin (FLM-TDX Abbott), associated or not with the presence of PG (PG positive). The latter phospholipid was present only in women whose pregnancy was about 35 weeks. Besides, our results show a very large disparity of the phospholipid rates (FLM-TDX) in the amniotic samples for an identical gestational age. Values from 9 to 124 for pregnancies with term of 31 weeks, and from 21 to higher than 160 for those of 38 weeks. In infants born not later than 48 hours after the amniotic punction (n = 30), four of them presented an HMD. The FLM-TDX values were less than 30 for three cases and equal to 52 for the fourth. The term of these newborns was 37 weeks or more for three of them, and 31 weeks for the last one. Our study confirm that the TDX-FLM Abbott is useful to assess the fetal lung maturity and does not correlate with the gestational age.