Russia and Iran are aiming to step up their business ties, as continued Western sanctions put pressure on their economies.
About 120 people from 65 Russian companies arrived in Tehran on Monday for a three-day business-promotion event.
The delegation is one of the largest ever to visit Iran from Russia.
About 650 firms from the host nation are taking part. They represent a wide variety of industries, including agriculture, forestry, manufacturing and healthcare.
Hassan Ghamari, the manager of an Iranian packaging-material maker, says, "If Russian companies have good technologies, then we hope to introduce and use them in Iran."
Business ties between the two countries are currently limited. Iranian customs officials say only about 3 percent of their imports come from Russia, which takes in only around 1 percent of Iran's exports.
But the sanctions could bring the two sides closer together.
US restrictions against Tehran continue over stalled negotiations aimed at reviving a 2015 nuclear deal.
Moscow is facing increasingly severe sanctions from the US and Europe over its invasion of Ukraine.