Objective of the research: to present the clinical and laboratory peculiarities of modern whooping cough in hospitalized children of different ages. Materials and methods: сlinical and laboratory characteristics of whooping cough were analyzed in 88 hospitalized sick children aged 1 month to 18 years in groups of children: group 1 – children under 1 year old; group 2 – children 1–6 years old; group 3 – children 7–17 years old. DNA of causative agents of pertussis infection was isolated by PCR in nasopharyngeal swabs using a commercial kit AmpliSens®Bordetella multi-FL (Moscow). Results: children of group 1 in 90% (n=43) of cases were not vaccinated against whooping cough, severe forms were recorded in 17% (n=8) of children of the 1st year of life, and in 15% (n=7) – due to respiratory rhythm disturbances. The diagnosis was confirmed by PCR in 94% (n=45) of children, leukocytosis with lymphocytosis was detected in 81,5% (n=101). Along with hematological changes typical for whooping cough, 79% (n=38) of patients in the first year of life had thrombocytosis (>400×109/l), which was most pronounced in severe disease course 511,5 [425; 568,5]×109/l vs 421 [347; 505,5]×109/l; p<0,05, which has no tendency to decrease throughout the entire observation period and correlates with the level of leukocytes (rs=0,69; p<0,001). Patients over 7 years old in 88% (n=21) of cases were vaccinated against whooping cough, but 79% (n=27) hemograms had no characteristic changes, which, along with a low frequency of confirmation of the diagnosis by PCR 22% (n=4), made it difficult to diagnose whooping cough. Conclusion: children over 7 years of age may not have characteristic hematological changes and PCR diagnostics are insufficiently effective, which contributes to the spread of whooping cough in family foci.