The aim of this study is to investigate maternal and fetal clinical parameters on maternal serum alpha-fetoprotein (MAFP) levels at late pregnancies. The studied subjects were 36 to 40 weeks pregnant. The pregnancies were singletons without any medical or gynecologic disease. Delivery followed within three days after blood sampling. A total of 192 subjects were included. The MAFP levels were measured by radioimmunoassay. The results showed the average MAFP was 108.2 ng/ml (SE 4.8 ng/ml). Male-fetus-bearers had higher MAFP (mean 121.4, SE 8.2 ng/ml, n = 84) than female-fetus-bearers (mean 97.9, SE 5.43 ng/ml, n = 108) (p = 0.014). MAFP did not have significant correlation with fetal weight (p > 0.05) regardless of whether the fetus was a male (p > 0.05) or female (p > 0.05). By stepwise multiple regression, fetal sex was revealed to be the only factor that can affect MAFP (p = 0.0071). MAFP did not correlate with maternal age, gravidity, parity, maternal weight, total weight gain during pregnancy, gestational weeks, or fetal weight (all p > 0.05). Since fetal sex is the only factor that influences MAFP levels at uncomplicated late pregnancies, MAFP values should be interpreted with caution.