Treatment of trichuriasis with single dose of albendazole or mebendazole gives low cure rate (CR). The purpose of this study aimed to know the effectiveness of double doses 500 mg mebendazole againts soil transmitted helminths (STH) infection in children aged 2-15 years. This study used a pre post design, conducted on July 2016-February 2017 in Perobatang village, Southwest Sumba. Effectiveness is assessed from CR and egg reduction rate (ERR). Stool samples were examined microscopically with Kato-Katz method. In total of 89 subjects, prevalence of STH, Ascaris lumbricoides and Trichuris trichiura infections were 79.8%, 46.1% and 76.4%. After administration of double dose 500 mg mebendazole the prevalence decresed to 39.3%, 2.2%, 39.3%. CR of A.lumbricoides was 95.1% and T.trichiura was 48.5% while ERR of each infection was 97.98% and 69.73%. There were significant difference in prevalence and ERR before and after treatment (p<0.001). In conclusions double doses 500 mg mebendazole was effective in treating A.lumbricoides but was not for T.trichiura. However, CR and ERR of double dose 500 mg mebendazole againts T.trichiura are higher than single doses.