After a two year vanishing act, President Tito's disgraced third wife Jovanka has finally reappeared in public - visiting a Belgrade cemetery.

The mystery of what happened to Jovanka, a former partisan nurse who married Marshal Tito in 1952, still continues to intrigue and fascinate Yugoslavs. No official explanation was ever provided for her disgrace, but dozens of theories were formulated ranging from deep political intrigues to a simple domestic tiff.

Still stout and wearing a billowing dress, Jovanka visited the cemetery last weekend in order to pay her respect to another woman partisan who died last month. Accompanied by a woman friend, she was driven to the cemetery in an official-looking car.

The presence of Yugoslavia's best-known "non-person" attracted considerable stares from other people in the cemetery. Several approached her to shake her hand.

A Belgrade journalist who spoke to Jovanka at the cemetery quoted her as saying: "As far as my health is concerned, I am fine - but I have very many problems." She did not elaborate.

Once Tito's constant companion, Jovanka has been out of bounds for the official press since June 1977. The efforts devoted to ensuring she was always pictured by Tito's side are now spent seeing that she never graces the pages of a Yugoslav newspaper again. But given her former prominence, it's a difficult task. Old shots occasionally contain telltale glimpses of a feminine elbow or knee impossible to crop out.

It has been even more difficult to expunge Jovanka's smiling face from the public imagination. Her fellow Serbs have a soft spot for underdogs and she has taken a martyr-like image since her disgrace.

Spotting the woman who has replaced Jovanka, 54, at the 87-year-old Tito's side has become a favorite game among Yugolslavs since her fall from grace. An unofficial tally of possible candidates includes an airline hostess, a journalist, a masseuse, and an opera singer.