Vadim Zakharovich Rogovin, the Russian Marxist historian and sociologist, and author of a monumental six-volume study of the Trotskyist opposition to the rise of the Stalinist regime within the USSR, died of cancer early Friday morning in Moscow. He was 61 years old.

A Doctor of Philosophical Sciences and leading researcher at the Institute of Sociology of the Russian Academy of Sciences in Moscow, Rogovin was among the most highly regarded sociologists in the Soviet Union.

However, in sharp contrast to virtually all his academic colleagues, Rogovin did not renounce his Marxist and socialist convictions during the years of Perestroika and in the aftermath of the collapse of the USSR.

Instead, Rogovin declared openly that he was an adherent of Trotskyism, and embarked upon the intellectual project that was to occupy him during the last decade of his life: the writing of the history of the Marxist opposition to Stalinism within the Soviet Union between 1923 and 1940.

The first volume, Was There An Alternative?, was published in 1992; and the second volume, Power and Opposition, appeared one year later.

In May 1994--during the writing of the third volume, Stalin's Neo-NEP, which placed the regime's preparation for the purges in the context of its repudiation of the egalitarian principles of the Bolshevik Revolution--Rogovin underwent surgery for cancer of the colon.

The surgeons discovered that the disease had already spread to the liver, and warned that Rogovin would be fortunate if he lived for another year.

Despite the grim prognosis, Rogovin intensified his intellectual efforts, completed the third volume, and decided to expand the scope of his project. Initially, he had planned to complete the historical study in four volumes. However, as access to previously closed archival material placed a wealth of new documents at his disposal, Rogovin concluded that his work could not be completed in less than seven volumes.

In the face of extraordinary physical adversity, Rogovin completed six of the planned seven volumes. Volume four, 1937: Stalin's Year of Terror, was published in 1996; volume five, The Party of the Executed, appeared in 1997; and volume six, World War and World Revolution, was published several weeks ago. At the time of his death, Rogovin was already drafting chapters of volume seven.

Rogovin's activities were not confined to research and writing. In 1993 he made contact with the International Committee of the Fourth International with which he developed a close political and intellectual relationship, and with whose program he publicly declared his solidarity. Between 1995 and 1998, he delivered lectures organized by the International Committee in the United States, Britain, Germany and Australia.

Vadim Rogovin is survived by his wife, Galina Valiuzhenich.