Médecins sans Frontières-Holland has treated > 67,000 patients with kala-azar (KA) in southern Sudan since 1989. In 2002, we replaced the standard regimen of 30 days of daily sodium stibogluconate (SSG) with a 17-day regimen of daily SSG combined with paromomycin (PM). We analyzed data for 4,263 primary KA patients treated between 2002 and 2005 in southern Sudan to determine the relative efficacy of the combination therapy regimen (PM/SSG). The initial cure rate among patients treated with PM/SSG was 97.0% compared with 92.4% among patients treated with SSG monotherapy. Relative efficacy of PM/SSG compared with SSG increased over the study period: odds of death in the PM/SSG group were 44% lower (odds ratio [OR] = 0.56, 95% confidence interval [CI] = 0.37-0.84) in 2002, 78% lower (OR = 0.22, 95% CI = 0.10-0.50) in 2003, and 86% lower (OR = 0.14, 95% CI = 0.07-0.27) in 2004-2005. In remote field settings, 17 days of SSG combined with PM gives better survival and initial cure rates than 30 days of SSG monotherapy.