The treatment for hydrocele is expensive, invasive surgery-hydrocelectomy. A drug that could prevent or improve this condition could replace or supplement hydrocelectomy. In Ghana, 42 hydrocele patients participated in a double-blind, placebo-controlled trial of a six-week regimen of doxycycline, 200 mg/day. Four months after doxycycline treatment, patients received 150 mug/kg of ivermectin and 400 mg of albendazole, which is used for mass chemotherapy in this area. Patients were monitored for levels of Wolbachia sp., microfilaremia, antigenemia, plasma levels of vascular endothelial growth factor-A (VEGF-A) and stage/size of the hydrocele. Wolbachia sp. loads/microfilaria, microfilaremia, and antigenemia were significantly reduced in the doxycycline-treated patients compared with the placebo group. The mean plasma levels of VEGF-A were decreased significantly in the doxycycline-treated patients who had active infection. This finding preceded the reduction of the stage of hydrocele. A six-week regimen of doxycycline treatment against filariasis showed amelioration of pathologic conditions of hydrocele patients with active infection.