The morbidity of insulin-dependent diabetes mellitus (IDDM) in children develops not evenly. Epidemiological leaps are periodically registered. This character of dynamics suggests the existence of environmental factors having the influence on the IDDM morbidity. One of these environmental factors is viral infection. We have set ourselves as an object to analyze the relationship between the primary morbidity of IDDM and some infectious diseases in children, to build up the prognostic models for the dynamics of IDDM morbidity and to evaluate their quality. Statistic analysis of the relationship between the primary morbidity of chicken pox, scarlet fever, measles, mumps, viral hepatitis, acute intestinal infectious diseases (AIID), acute upper respiratory infections (AURI) and insulin-dependent diabetes mellitus in children of Grodno region covering the period from 1980 to 2001 years has been performed. It has been established, that morbidity rate of IDDM reliably positively correlated with morbidity of AURJ and AIID (accordingly r=0.62; and p=0.02 and r=0.46; p=0.04) and negatively with the scarlet fever and mumps morbidity (accordingly r=-0.55; p=0.008 and r=-0.53; p=0.01). But cluster analysis has shown, that really only indices of AURI and AIID morbidity were connected and formed one cluster. Morbidity rate of IDDM in children in the current year is most closely connected with AURI and AIID frequency in the previous year, but frequency of the above-mentioned infections registered in the same year influences less on diabetes morbidity, not mentioning the infections of 2-years standing which practically have no influence. If the increase in AURI morbidity accounts for 10% as compared to the previous year one may prognosticate with high reliability an increase of primary morbidity of IDDM by 7.7% on the average during the same year, and by 8.3% in the following year. For AIID these indices account for 3.5% and 4.4% correspondingly. In the increase of the morbidity rate of AIID the morbidity rate of IDDM reduces.