Surveillance for Lyme disease (LD) was initiated by CDC in 1982 (1), and in January 1991, LD became nationally reportable (2). Forty-six states reported cases in 1989 and 1990 (Figure 1), but the occurrence in nature of the causative bacterium, Borrelia burgdorferi, has not been documented in all of these states. From 1982 through 1989, the annual reported number of cases of LD increased 18-fold (from 497 to 8803, respectively) and from 1986 through 1989, nearly doubled each year (Figure 2). The provisional total of 7997 cases for 1990 suggests a plateau in this trend of rapid annual increase. This report summarizes surveillance of LD during 1990 in Connecticut, Georgia, Michigan, Missouri, New Jersey, and Wisconsin.