Abstrak Berbagai macam metode kontrasepsi tersedia baik berupa metode hormonal maupun metode non hormonal. Data Riskesdas 2018 menunjukkan KB suntik 3 bulan merupakan kontrasepsi hormonal yang paling banyak digunakan. Setiap kontrasepsi hormonal yang ada mempunyai efek samping termasuk KB suntik 3 bulan yang mengandung progestin. Dari data register yang diambil di PBM Desa Suko Kabupaten Sidoarjo, akseptor KB suntik 3 bulan hampir seluruh akseptor mengalami efek samping, Tujuan penelitian mengkaji efek samping KB suntik 3 bulan terhadap kelangsungan penggunaan KB suntik 3 bulan. Desain penelitian yang digunakan desain penelitian korelasi dengan menggunakan pendekatan cross sectional dengan studi retrospektif. Populasi pada penelitian seluruh akseptor KB suntik 3 bulan yang mengalami efek samping (spotting) di PBM Desa Suko Kabupaten Sidoarjo berjumlah 34 akseptor dan sampel yang diambil 31 akseptor.Teknik sampling menggunakan random sampling. Uji statistik Chi-Kuadrat dengan taraf signifikan 0,05 didapatkan 2X sebesar 2,981823 sedangkan 2X tabel Chi-Kuadrat dengan d.b=1 sebesar 3,481. Jadi didapatkan hasil 2X hitung lebih kecil dari 2X tabel Chi-Kuadrat maka hipotesa Ho diterima. Kesimpulan efek samping (spotting) tidak ada hubungan dengan kelangsungan penggunaan KB suntik 3 bulan.Kata kunci: efek samping, spotting, kontrasepsi, KB suntik Abstract There are various contraceptive methods available, both hormonal and non-hormonal methods. The 2018 Riskesdas data shows that 3 months injection contraceptive is hormonal contraceptive most used. Every hormonal contraceptive has side effects including 3 months injection contraceptive that contains progestin. Based on registered data taken at PBM (Independence Midwife Practice) Suko village, Sidoarjo, almost all acceptors of 3-month injection contraceptive experience side effects, therefore researchers want to study side effects of 3-month injection contraceptive toward the continuity of using 3-month injection contraceptive. The research design used correlation research design using a cross sectional approach with a retrospective study. Population in study was 34 acceptor of 3 month injection contraceptive who experienced side effects (spotting) in PBM Suko village, Sidoarjo and the sample was 31 acceptors. Sampling technique uses random sampling. Chi-Square statistical test with a significant level of 0.05 was obtained 2X of 2.981823 while the 2X Chi-Square table with d.b = 1 was 3.481. So the result is 2X count smaller than 2X Chi-Square table, so the Ho hypothesis is accepted. Conclusion of this study is that side effects (spotting) have no relationship with continuity of using injection contraceptives for 3 months.Keywords: side effect, spotting, contraception, injection contraceptive