Tanzania's President Samia Suluhu Hassan has arrived in Kigali on her first official visit to Rwanda.
She is expected to hold talks and have a joint press conference with President Paul Kagame later in the day.
Tanzania is the second-biggest exporter to Rwanda, after China.
President Samia’s two-day visit is aimed at strengthening relations, and the pair will sign several trade agreements.
The two leaders are also expected to discuss the first stages of a $3.6bn (£2.6bn) railway project which was agreed in 2018. The 532km (856 miles) railway will link Isaka in northern Tanzania with the Rwandan capital.
Also expected on the agenda is a discussion about the militant Islamist insurgency in Mozambique's Cabo Delgado region, which borders Tanzania and where Rwanda has already deployed 1,000 troops.