Objectives: To investigate the effect of chemotherapy cycles on survival outcomes in small cell neuroendocrine carcinoma of cervix (SCNEC). Methods: Clinical records of 103 biopsy-proven SCNEC were identified from Sun Yat-sen University Cancer Center. The cycles-dependent effect of chemotherapy on survival was estimated by restricted cubic splines (RCS) based cox regression model. Results: Through RCS analysis, we observed an inverse correlation between chemotherapy cycles and progression/death; the risks (hazard ratio [HR]) of progression/death decreased sharply until 5 cycles of chemotherapy. Long-course chemotherapy (≥5 cycles) was associated with significantly superior PFS (≥5 vs 1-4: median PFS, 58.6 months vs 25.4 months, P =0.027) and prolonged OS (≥5 vs 1-4: median OS, 65.1 months vs 37.7 months, P =0.168) than short-course chemotherapy (1-4 cycles). Subgroup analyses suggested that chemotherapy courses had significant interaction with FIGO stage; the survival benefit of long-course chemotherapy was identified in FIGO IIB-IIIC (HRPFS 0.41, 95% CI 0.18-0.92; HROS 0.41, 95% CI 0.17-0.95), rather than FIGO I-IIA (HRPFS 0.67, 95% CI 0.34-1.34; HROS 0.88, 95% CI 0.40-1.97). Additionally, chemotherapy regimen was observed to be relevant to survival outcomes; EP regimen demonstrated obvious prolonged PFS (median PFS: EP vs non-EP, 44.7 months vs 18.0 months) and OS (median OS: EP vs non-EP, 63.3 months vs 41.0 months) than those treated with non-EP regimen. Conclusion: Chemotherapy with ≥5 cycles significantly improved PFS and OS in FIGO stage IIB-IIIC SCNEC, whereas a short course of <5 cycles was adequate for FIGO I-IIA disease.