Introduction. Data examining mammographic breast density (MBD) among patients in Sub-Saharan Africa are sparse. We evaluated how MBD relates to breast cancer characteristics in Kenyan women undergoing diagnostic mammography. Methods. This cross-sectional study included women with pathologically confirmed breast cancers (n=123). Pretreatment mammograms of the unaffected breast were assessed to estimate absolute dense area (cm2), nondense area (cm2), and percent density (PD). Relationships between density measurements and clinical characteristics were evaluated using analysis of covariance. Results. Median PD and dense area were 24.9% and 85.3 cm2. Higher PD and dense area were observed in younger women (P<0.01). Higher dense and nondense areas were observed in obese women (P-trend < 0.01). Estrogen receptor (ER) positive patients (73%) had higher PD and dense area than ER-negative patients (P≤0.02). Triple negative breast cancer (TNBC) patients (17%) had lower PD and dense area (P≤0.01) compared with non-TNBCs. No associations were observed between MBD and tumor size and grade. Conclusions. Our findings show discordant relationships between MBD and molecular tumor subtypes to those previously observed in Western populations. The relatively low breast density observed at diagnosis may have important implications for cancer prevention initiatives in Kenya. Subsequent larger studies are needed to confirm these findings.