A cross-sectional study with a convenience sample of 241 patients with breast cancer was conducted to investigate death depression and its explanatory factors in Iranian women who were diagnosed and undergoing treatment for breast cancer. Patients with significantly higher death depression were those who were housewives (β = 0.6, p = 0.016), unskilled workers (β = 15.8, p = 0.002), and retired (β = 13.1, p = 0.002) as compared with those who were professionally employed with higher socio-economic status (β = 17.4, p = 0.002); and those receiving combination therapy as compared to surgery only (β = 6.3, p = 0.02). For patients with higher spiritual health scores, death depression was significantly lower (β = -0.2, p < 0.001).