Increased left ventricular mass (LVM) on echocardiogram is an independent risk factor for cardiac complications from hypertension. It is associated with a four-fold increase in untoward cardiac events when present. Data were reviewed for 100 treated hypertensive Afro-Caribbean patients, aged 29 to 65 years, recruited from village health clinics. Age, gender, height, weight, systolic and diastolic blood pressure, echocardiogram (ECHO) and drug history were recorded for each patient. The best single predictor of increased LVM was blood pressure with systolic (163 vs 152 mmHg, p < 0.01) and diastolic blood pressure (105 vs 98, p < 0.01) being significantly higher in patients with increased LVM. Systolic blood pressure over 150 mmHg was associated with increased LVM in 64% vs 44% below 150 mmHg (p < 0.10). Diastolic blood pressure over 95 mmHg was associated with increased LVM in 63% vs 36% below 95 mmHg (p < 0.02). BMI showed a trend (31.1 vs 29.7 kg/m2, p < 0.20) toward higher values in patients with increased LVM. BMI above 28 kg/m2 was associated with increased LVM in 61% vs 44% below that value (p < 0.15). Females more than males had increased LVM (61% vs 44%, p = 0.30) possibly due to higher BMI (31 vs 29.4 kg/m2) and higher systolic blood pressure (160 vs 155 mmHg). Age (48.3 vs 46.5 years, p = 0.30) and years of hypertension (8.6 vs 7.3 years, p = 0.33) were not significantly different between the two groups. Drug treatment was reported in 90% (69% monotherapy, 27% > one drug, 4% > 2 drugs) and no drug was associated with significant difference in LVM compared to others. Only 15% of treated hypertensive patients had systolic blood pressure below 140 mmHg and 8% had diastolic blood pressure below 90 mmHg. The major determinant of increased LVM in this group of Afro-Caribbean hypertensive patients appears to be poorly controlled hypertension with obesity being a possible contributing factor.