Chlamydia trachomatis  is the most common bacterial pathogen causing sexually transmitted infections. As prenatal screening for C. trachomatis and treatment of pregnant women is not practice in Slovenia, perinatal transmission of C. trachomatis may therefore occur. We present a case of infant chlamydial pneumonia to illustrate that a high index of suspicion is necessary to make the diagnosis in an afebrile infant with cough and “bronchiolitis”. Unnecessary investigations can be avoided and treatment can be promptly instituted if a diagnosis is made  on time.