But despite the 65-year-old President's pledge to be open about his condition, Sergei Yastrzhembsky, his spokesman, declined to release any details about the nature of the tests, or when his heart bypass operation is expected to take place.
Mr Yastrzhembsky said only that doctors had recommended complete rest during the "final stage of preparations" for the operation, and that Mr Yeltsin "will undergo a whole series of medical tests under a special regime in the next few days".
The abrupt cancellation of Mr Yeltsin's appointments, including his weekly meeting with the Prime Minister, Viktor Chernomyrdin, will spawn another squall of speculation over the President's state of health.
On the one hand, the decision will raise suspicions that he may have taken a downward turn: if the tests were planned in advance, as the Kremlin yesterday suggested, why were the meetings scheduled in the first place? Why did Mr Yastrzhembsky say, four days earlier, that there would be "no change to the schedule laid down for the operation", but make no mention of the pending tests?
Such queries may seem unduly conspiratorial but Kremlin watchers have not forgotten the tide of official falsehoods saying that Mr Yeltsin was suffering only from exhaustion and a cold after he disappeared from public view in June. Later it emerged that he may have had another heart attack between the two rounds of the presidential elections.
On the other hand, Mr Yeltsin is said to be anxious to have the operation as quickly as possible. His doctors have said they expected to go ahead in the second half of November, although Mr Yastrzhembsky yesterday sounded more vague, saying that there were no grounds to believe his operation will go ahead this week.
Certainly, there is an urgent need for Mr Yeltsin to reassert his authority. Last week he reprimanded his top officials for squabbling, after an outbreak of infighting among several of his most senior staff, notably General Anatoly Kulikov, the Interior Minister, and Alexander Lebed, the national security adviser, who was fired on 17 October.
As alarming, from Mr Yeltsin's viewpoint, is that several Kremlin insiders, including General Alexander Korzhakov, his former confidant and chief bodyguard, have suggested that he is out of touch, and that the country is being run regency-style by Anatoly Chubais, his chief-of-staff aided by Mr Yeltsin's daughter, Tatyana Dyachenko.
Yesterday, Mr Yeltsin counter-attacked by stripping the general of his military rank.