A 1986 audit of self-administered anti-tuberculous prophylaxis (SAP) revealed a compliance rate of 25% at six weeks, 8% at 16 weeks, and 5% at 52 weeks. A short affordable program of daily observed prophylaxis (DOP) and education was developed to improve the compliance rate. The sustaining influence of a six week intervention on one year of prophylaxis was determined. Forty-two of 114 (37%) eligible patients began chemoprophylaxis and were randomly assigned to two groups - 21 in Group 1 with DOP and education, and 21 in Group 2 with SAP and education. After six weeks, Group 1 compliance was greater than 1986 compliance (p less than 0.001) and greater than Group 2 compliance (p less than 0.05), and Group 2 compliance was greater than 1986 compliance (p less than 0.01). At 16 weeks, 10 weeks after DOP and education were discontinued, the compliance of the three groups was not different. Since 63% of persons who represent potential future tuberculosis were lost in the evaluation process before starting preventive treatment, and 5% of those who began preventive treatment completed treatment, only 2% of potential future tuberculosis was prevented. DOP and education significantly improved compliance but the improvements were not sustained after DOP and education were discontinued.