The efficacy of 2 strategies for the control of bancroftian filariasis using diethylcarbamazine (DEC) mass chemotherapy delivered through community participation was evaluated and compared in 2 endemic communities in Tanzania with pre-treatment microfilarial (mf) prevalences of 34.7% and 31.0%, and mf geometric mean intensities (GMI) of 1122 mf/mL and 933 mf/mL, respectively. In the first community, all individuals aged > or = 1 year were offered treatment for one year with a low monthly dose (50 mg DEC to children aged < 15 years and 100 mg DEC to adults aged > or = 15 years; given independently of body weight), and in the second community all households were offered 0.33% w/w DEC-medicated cooking salt for one year. Both treatment strategies resulted in dramatic reductions in the mf loads. Among those microfilaraemic before treatment, the low monthly dose and the DEC-medicated salt gave mf clearance rates of 55.3% and 92.1%, respectively, and the pre-treatment mf GMIs were reduced by 99.4% and 99.9%, respectively, one year after starting treatment. At community level, the mf prevalences were reduced to 15.8% and 2.4% (reductions of 54.5% and 92.3%) and the mf GMIs were reduced to 100 mf/mL and 32 mf/mL (reductions of 91.1% and 96.6%), one year after starting treatment with the low monthly dose and DEC-medicated salt respectively. Males with hydrocele before treatment improved remarkably one year after the start of treatment. Since both strategies were simple to administer and well accepted by the communities, they appear highly feasible for integration into large scale control programmes based on community participation.