Imunisasi merupakan upaya memberikan kekebalan pada anak dengan memasukkan vaksin ke dalam tubuh agar tubuh membuat zat antibodi untuk mencegah penyakit tertentu. Kelengkapan imunisasi dipengaruhi oleh banyak faktor antara lain usia ibu, pekerjaan ibu, pendidikan terakhir ibu, pendapatan keluarga, ketakutan akan efek samping imunisasi, tradisi keluarga dalam pemberian imunisasi, larangan agama, pengetahuan tentang jadwal imunisasi, jarak tempat pelayanan, biaya imunisasi, dan rumor buruk tentang kandungan vaksin. Tujuan penelitian ini mengetahui faktor-faktor yang memengaruhi cakupan imunisasi dasar di Puskesmas Cijagra Lama Kota Bandung periode Agustus−November 2019. Desain penelitian adalah deskriptif dengan pendekatan cross sectional. Data hasil penelitian dianalisis univariat untuk menghitung distribusi, frekuensi, karakteristik responden, dan karakteristik setiap variabel penelitian. Sampel penelitian adalah ibu yang datang ke Puskesmas Cijagra lama Kota Bandung dengan membawa bayi berusia 0−24 bulan yang akan dilakukan imunisasi dasar. Pengambilan sampel dengan cara total sampling. Besar sampel sebanyak 139 responden. Hasil penelitian ibu yang membawa anaknya untuk imunisasi dasar lengkap didominasi oleh ibu yang berusia <30 tahun (57,1%), ibu rumah tangga (84,2%), pendidikan terakhir SMA dan perguruan tinggi (86,5%), sedangkan pendapatan keluarga hampir sama antara di bawah Upah Minimum Regional (UMR) dan di atas UMR. Responden yang anaknya diimunisasi dasar lengkap mayoritas tidak takut akan efek samping (p=0,006), sudah tradisi untuk diimunisasi (p=0,214), tidak ada larangan agama (p=0,02), mengetahui jadwal imunisasi (p=0,023), jarak tempat pelayanan imunisasi tidak terlalu jauh (0,004), biaya masih terjangkau (p=0,603), serta tidak perduli akan rumor buruk tentang kandungan vaksin (p=0,877). Responden yang tidak melakukan imunisasi dasar lengkap, mayoritas usia ibu ≥30 tahun, ibu rumah tangga, pendidikan SMA dan perguruan tinggi, dan pendapatan keluarga di bawah UMR. Simpulan, faktor yang memengaruhi cakupan status imunisasi dasar adalah ketakutan akan efek samping, larangan agama, pengetahuan jadwal imunisasi, dan jarak tempat pelayanan imunisasi. FACTORS AFFECTING BASIC IMMUNIZATION COVERAGE IN PUSKESMAS CIJAGRA LAMA BANDUNG CITYImmunization is an attempt to provide immunity to children by introducing vaccines into the body so that the body makes antibodies to prevent certain diseases. Completeness of immunization is affected by many factors including mother’s age, mother’s occupation, mother’s last education, family income, fear of immunization side effects, family traditions in immunization, religious restrictions, knowledge of immunization schedules, the distance of services, immunization fees, and bad rumors about vaccine content. The purpose of this study was to determine the factors that affecting the basic immunization coverage in the Cijagra Lama Health Center in the City of Bandung in the August– November 2019 period. The study design was descriptive with a cross- sectional approach. Data were analyzed univariate to calculate the distribution, frequency, characteristics of respondents, and characteristics of each study variable. The sample of this research was mothers who come to the old Cijagra Health Center in Bandung City with babies aged 0−24 months who will be given basic immunizations. Sampling by total sampling. The sample size was 139 respondents. The results of the study of mothers who bring their children to complete basic immunizations were dominated by mothers aged <30 years (57.1%), housewives (84.2%), high school education and college (86.5%), while income almost the same family between below regional minimum wage and above regional minimum wage. Respondents whose children were fully immunized basic majority were not afraid of side effects, it was tradition to be immunized, there was no religious prohibition, knowing the immunization schedule, distance between immunization services was not far, the cost was still affordable, and no matter the bad rumors about vaccine content. Respondents who did not complete basic immunization, the majority of mothers aged ≥30 years, housewives, high school and college education, and family income below regional minimum wage. In conclusion, that most of the coverage of basic immunization status at the Cijagra Lama Health Center in Bandung are complete, and the small part that is incomplete is influenced by maternal age ≥ 30 years, family income below regional minimum wage, less knowledge about immunization.