Surveys for external quality assessment in blood banking were carried out in 1999. The response rate was 86.9% for 1st trial, 82.9% for 2nd trial, and 85.4% for 3rd trial. Test items were ABO cell and serum groupings, Rho(D) typing including DU test, crossmatching, direct antiglobulin test, antibody screening and identification test. The average accuracy rates of ABO cell and serum grouping were more than 99.3%. The accuracy rates of Rho(D) typing were 100% for positive samples, 99.3% for negative ones, and 99.4% for DU samples. The average accuracy rates of cross-matching were 96% for compatible samples, 98% for incompatible samples which could be detected by saline method, and 83% for incompatible samples which could be detected only by 37degrees C albumin, and 100% for an incompatible sample which could be detected by antiglobulin method, The accuracy rates of direct antiglobulin test were 96.6% for negative samples and 91.2% for positive samples. The accuracy rates of antibody screening and identification tests were all 98.0%.