Mycoplasma pneumoniae and Chlamydia sp. frequently cause atypical pneumonia in children. The study aim was the analysis of clinical picture of pneumonia caused by Mycoplasma pneumoniae and Chlamydia sp. in 278 children treated in the period of 1985-1998 in the IInd Clinic of Pediatrics and Gastroenterology, Medical Academy of Wrocław. The influence of etiological factor and age of children for the clinical picture of the disease was estimated. The most characteristic clinical symptom of the atypical pneumonia in children was "staccato" cough observed in 89.9% of children. More severe course of the mycoplasmal pneumonia in comparison with that of Chlamydia origin was demonstrated. The most severe course of pneumonia was observed in infants. The afebrile course of the disease was observed in the group of Chlamydia pneumonia (in 26.3% of infants, 40% of children aged 1-6 years and 54.8% of children aged 7-15 years). None of children with mycoplasmal pneumonia had an afebrile course of the disease. The most characteristic radiological picture in children with atypical pneumonia were diffused, symmetrical interstitial inflammatory changes of the lungs. In the group of children with mycoplasmal pneumonia in over 50% of cases the enlargement of lymph nodes of the lungs hili were observed.