The government remains committed to reforms but without a strong leader in charge, economic policy can drift dangerously, they said.
Yeltsin, hit by heart trouble during his election campaign last June and sent to hospital with pneumonia last week, has left a government of unelected officials to run the country and make economic policy.
The Russian economy shrank by about five percent in 1996 and despite official promises that it will grow this year, only Yeltsin, who has enormous powers under the constitution, can approve many structural reforms needed to sustain recovery, analysts say.
Russia has eliminated hyperinflation and won international respect from borrowers with a debut Eurobond last November but important reforms remain to be made.
Officials predict that growth will be flat this year while much of Russian industry is caught in a barter economy, without access to credit and with enormous debts to workers, energy providers, the government and each other.
Yeltsin`s administration is generally pro-reform but without Yeltsin, there is no one to choose which reforms, said Roland Nash, chief economist at Renaissance Capital bank.
U.S. Deputy Treasury Secretary Lawrence Summers said last week Russia needed to recapture the momentum of market reforms - otherwise the economy would stagnate and, in particular, it needed to restructure the tax system. But some analysts and foreign investors who drove Russian shares to record levels last week argue that Yeltsin`s absence is irrelevant.
Miljenko Horvat, Citibank N.A. vice president and manager of a fund set up to invest in Russia, said reforms were safe. Horvat said the government and economic machine appeared to be performing adequately in Yeltsin`s absence. "It all seems fairly comfortable at the moment. Things are as good as anyone could expect."