Background: To provide information on the prevalence of transmissible viral disease in a Thai cohort of 2101 consecutive maternal blood samples of autologous umbilical cord blood (UCB) stored in a private cord blood bank. Materials and methods: Transmissible viral disease screening in 2101 consecutive maternal blood samples was performed serologically using the CMIA technique on an Architect i1000SR for Hepatitis B Virus (HBV) (HBsAg and Anti-HBc), Hepatitis C Virus (HCV) (anti-HCV), Human Immunodeficiency Virus (HIV) (HIV Ag/Ab Combo), Human TLymphotropic Virus type 1 and 2 (HLTV 1/2) (Anti-HTLV 1/2) and Cytomegalovirus (CMV) (CMV-IgG and CMV-IgM). Nucleic Acid Tests (NAT) were used as confirmatory tests for HBV, HIV and HCV. The prevalence of transmissible viral disease and comparisons between serological screening and NAT testing were studied and reported in this study. Results: In 2101 consecutive maternal serum samples, the positive rate of HBV-NAT was 1.62%, HCV-NAT was 0.14%, HIV-NAT was 0%, HBsAg was 2.52%, anti-HBc was 16.85%, anti-HCV was 0.33%, and HIV Ag/Ab combo was borderline but finally negative in one case. In HBsAg positive samples the positive rate of HBV-NAT was 64.15% while in anti HBc positive samples, the positive rate of HBV-NAT was 9.6%. In anti HCV positive samples, the positive rate of HCV-NAT was 42.86%. The positive rate of HTLV 1/2 was 0% and borderline in 0.19% but finally reconfirmed negative in all cases. The positive rate of CMV-IgG was 86.53% while CMV-IgM was 0.33%. Conclusions:In the present study, in a Thai cohort of maternal blood samples of autologous UCB stored in a private cord blood bank, very low prevalence of transmissible viral disease was noted. HBV, HCV and CMV prevalences were lower than observed in the general Thai population, possibly due to widespread of vaccine immunization, and the higher socioeconomic status of the mothers opting for private UCB banking. Due to our screening procedures, HIV could not be detected in any of the maternal sera. HTLV 1/2 could not be detected in any of the samples and this is the first report of its prevalence in Thailand in almost 20 years. The low prevalence of CMV IgM reinforces UCBs advantage in HSCT. The molecular biology techniques would make up for the default of the serological methods.