From 1950 through 1971, the reported infant mortality rate in the Soviet Union declined; between 1971 and 1975, it increased. Even by 1985, the reported rate exceeded that published for the late 1960s. It is argued here that the evidence for a real increase in infant mortality in the Soviet Union since 1971 is weak. The Soviet Union's definitions of live birth and infant death make reported Soviet infant mortality rates highly variable when minor improvements in registration procedures are made. Efforts to increase the completeness of registration could have induced higher reported infant mortality rates beginning around 1970. The official Soviet definition of infant mortality differs from World Health Organization recommendations. Because of this difference, even if registration of infant deaths were complete, the reported Soviet infant mortality rates should be adjusted upward by some 22-25 percent to make them consistent with the WHO definition.