The World Health Organization (WHO) recommends the use of tachypnea as a proxy to the diagnosis of pneumonia. The purpose of this study was to examine the relationship between body temperature alterations and respiratory rate (RR) difference (RRD) in children with acute respiratory infections(ARI). This cross-sectional study included 297 children with age 2-60 months who presented with cough and fever at the pediatric emergency and outpatient clinics in the Department of Pediatrics, Baskent University Hospital, from January 2016 through June 2018. Each parent completed a structured questionnaire to collect background data. Weight and height were taken. Body temperature, respiratory rate, presence of the chest indrawing, rales, wheezing and laryngeal stridor were also recorded. RRD was defined as the differences in RR at admission and after 3 days of treatment. Both respiratory rate and RRD were moderately correlated with body temperature (r=0.71, p<0.001 and r=0.65, p<0.001; respectively). For every 1°C increase in temperature, RRD increased by 5.7/minutes in overall, 7.2/minute in the patients under 12 months of age, 6.4/minute in the female. The relationship between body temperature and RRD wasn't statistically significant in patients with rhonchi, chest indrawing, and low oxygen saturation. Respiratory rate should be evaluated according to the degree of body temperature in children with ARI. However, the interaction between body temperature and respiratory rate could not be observed in cases with rhonchi and severe pneumonia.