The company reported highlights including 14m at 10.5g/t gold from 134m and 1.21m at 79.7g/t gold from 177m in another hole at Galgouli.
It also described "excellent results" following up historic drilling at Fofora, in Boussoura's north, such as 10.7m at 18.1g/t from 77.4m and including 0.86m at 98.1g/t from 81.2m.
President and CEO John Dorward said the company's exploration team had had "tremendous" success, with the discovery following the significant resource increase announced last week for its advancing Séguéla gold project in Côte d'Ivoire.
"We have a very attractive growth pipeline and are well positioned to deliver on our aspirations of being the next West African multi-asset gold producer," he said.
The company has two rigs continuing drilling at Boussoura.
Vice president exploration Paul Weedon said the results were setting up the potential for Roxgold's third high-grade gold project.
He said the company had identified at least nine other significant vein sets with artisanal workings where rock chips had indicated the potential for further high-grade mineralisation.
Roxgold expects to produce 120,000-130,000oz annually over the next three years at Yaramoko.
It has about US$42 million in cash according to a February presentation.
Its shares have ranged from C80c-$1.42 over the past year and lost 2.9% to $1.01 yesterday to capitalise it at $375.3 million (US$282.4 million).