A survey to evaluate the effectiveness of DPT immunization was carried out consisting of serological assay and coverage in 3 regencies in West Nusa Tenggara Province. The sample consists of 630 children, 1-2 years of age in the regencies of Central and East Lombok, in Lombok Island, and Bima in Sumbawa Island. Cluster sampling (WHO) was applied as sampling method. Thirty clusters were selected from each regency, and from each cluster 7 children were selected. Mothers were interviewed, and 0.1 ml of blood was taken from each child. Antibodies against diphtheria and tetanus were measured by Passive Haemagglutination (PHA) test, and antibodies against pertussis were measured by micro agglutination test. The average of coverage immunization of DPT 3 in 3 regencies in NTB province (88.57%) did not show significant differences if compared with the coverage reported from 1989 and 1990. Immunization with DPT 1, 2, and 3 in regencies of Central and East Lombok showed higher coverage compared to Bima. The utilization of KMS cards in 3 regencies is 52.38%. The average percentages of protected children against diphtheria, pertussis and tetanus 1-2 years post complete DPT vaccination were 65.10%, 30.08%, and 98.10% respectively. The average means of antibodies titers against diphtheria, pertussis and tetanus were 0.036 IU/ml, 35.328% U/ml and 1.665 IU/ml respectively. The immune response against pertussis in Bima was very low, which is probably be due to constraints in cold chain handling during vaccine transportation, and low utilization of KMS cards, resulting in inaccurate information on immunization status.