Iranian and western businessmen say some tentative deals have been prepared, ready for signature once the interim nuclear agreement struck in Geneva last month is implemented.
The visiting companies – mostly from France and Germany, but also from Italy and Austria – include car makers, miners, energy groups, transporters and manufacturers. They are examining expansion in Iran, while stressing their compliance with sanctions that restrict investment and sales.
"Companies are hungry for a new market due to the bad financial situation in the rest of the world," said one Italian consultant in Tehran.
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Under the terms of last month's interim deal, the main oil and banking sanctions will remain in place but restrictions on the Iranian car and petrochemicals sectors will be loosened and frozen assets valued by the US administration at $6bn-$7bn will be released.
Darmstadt-based Merck said it was in discussions with several specialist Iranian producers to assess production of two drugs, adding to its existing sales of medicines into the country.
(Read more: Merck earnings top estimates)
Sanofi of France, which already licenses production of several of its cancer drugs to a local Iranian manufacturer and employs 170 of its own staff in the country, said: "We are planning additional product launches next year in Iran. It's a good, solid business."
Medicines are among the humanitarian exemptions to the existing sanctions regime, but foreign companies' sales and investment have been limited by difficulties in payment, insurance and shipping.