Cystic fibrosis (CF), caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, is one of the most common autosomal recessive diseases in Caucasians. We screened for the CFTR gene mutation in a Caucasian father with congenital bilateral absence of the vas deferens (CBAVD), a Taiwanese mother, and twins resulting from an intracytoplasmic single sperm injection (ICSI) procedure. DNA fragments that showed abnormal banding patterns on temporal temperature gradient gel electrophoresis analysis followed by analysis of DNA sequence was used. The Caucasian father with CBAVD had _F508 and p.L375F mutations. The two children were heterozygous for the _F508 and p.L375F mutations, respectively. Mutation analysis of the CFTR gene should always be recommended for infertile couples seeking ICSI. The possibility of the children resulting from ICSI being a victim or carrier of CBAVD or CF, especially when the father is Caucasian with CBAVD, should be discussed during genetic counseling.