Parental decision-making to terminate or continue a pregnancy was studied after prenatal diagnosis of a chromosome aneuploidy among a sample of patients around the city of Nagoya, Japan. A total of 1,051 amniocentesis cases at 15-18 weeks of gestation were analyzed. Of these, 60 cases of chromosomal anomalies with aneuploidies were diagnosed by conventional cytogenetic analysis. Of the 45 diagnoses of autosomal chromosome aneuploidies, pregnancy was terminated in 93.3 % of the cases. Of the 15 cases diagnosed with sex chromosome aneuploidy, pregnancy was terminated in 46.7 %. Differences in parental decisions with respect to maternal age, gestational week at diagnosis, number of pregnancies per individual and existing number of children were not significant in patients diagnosed either with autosomal or sex chromosome aneuploidy. The findings indicate that when diagnosed with a chromosome aneuploidy in which a severe prognosis was expected, most couples decided to terminate the pregnancy in Japan. Implications of these findings for expanding the profession of genetic counseling are discussed and research recommendations are provided.