The universally accepted terms Lyme disease of Lyme borreliosis actually apply to the whole group of etiologically independent diseases. This group of diseases is designated as ixodid tick-borne borrelioses (ITBB) in contrast to argasid tick-borne borrelioses (ATBB) associated with soft ticks. Analysis of individual, etiologically specific diseases should be the matter of strategy in researches and diagnostic studies of ITBB. The prevalence of B. garinii and B. afzelii in the greater part of Eurasia is now beyond doubt. To date, ITBB cases have been registered in 46 of 50 Russian regions inhabited by I. persulcatus and I. ricinus ticks. Therefore, a considerable or even a great part of the world range of infections currently collectively called Lyme disease (LD) is located on the territory of Russia. The mean ITBB incidence rates in 1993-1994 was 3.1 per 100,00 inhabitants. Data reflect a considerable progress in ITBB diagnosis, made in the past two or three years rather than an increase in morbidity rates. The greatest incidence of ITBB is registered in the Ural and west Siberian regions (27 and 17.2%, respectively). In the following years, provided IBBT diagnosis and surveillance are properly organized, the eastern regions of Russia would account for the highest ITBB morbidity. Prognosis is that at least 10,000 to 12,000 new ITBB cases may be annually detected in Russia. ITBB affects mainly adult able-bodied persons. However, in 1993-1994 children under 14 years of age accounted for 1.4% of the total number of cases in Russia. On the whole, the proportion of city dwellers among ITBB patients was 84%, amounting to as high as 90-94% in some regions. The mean ITBB morbidity rate for the rural population in 1993-1994 was 1.8 per 100,000 inhabitants. In 1993-1994 IFA was regularly performed only in 21 regions. Analysis of paired serum samples obtained from suspected ITBB patients in due time yielded positive results in 65-70% of cases. To identify fresh ITBB cases more thoroughly, at least 200,000 persons should undergo serological testing every year. This number is approximately 25 times greater than the actual number of these tests annually performed in Russia. In this connection, IFA will retain for several years its contribution to a conventional laboratory test routinely used in Russia.