The effectiveness of two social support strategies designed to lower hypertensive patients' blood pressure were compared to each other and to a control group (N = 63) receiving routine care in a randomized clinical trial extending over a period of two years. Group 1 (N = 99) received visits and had family members actively participate in their care through home blood pressure monitoring; Group 2 (N = 56) received home visits from nurses and pharmacists. All groups were predominantly Black. After the first year of the trial, the proportion of patients with uncontrolled diastolic blood pressure (greater than or equal to 95mm Hg) had declined significantly for all three groups; no group showed a statistically significant advantage. However, during the last six months of the second year (after visiting had ended), both Groups 1 and 2 demonstrated clear superiority in DBP control over Group 3, achieving borderline statistical significance (p = .07) when multivariable analysis was performed to control for potential confounders. Supplementing routine care with periodic home visits produced an additional 21 per cent of patients with well-controlled DBP, while involving family members plus visits produced a 17 per cent improvement in the percentage of patients with DBP less than 95mm Hg. However, neither support strategy was clearly more effective than the other over time. The efficacy of the interventions is discussed with respect to cost and feasibility of implementation.