The natural history of asthma is not well known; its origin may go back to just after the birth. The aims of this study are: 1) studying the evolution of the symptomatology of a group of children suffering from recurrent asthmatic bronchitis of a moderate-severe level in the first two years of life; 2) inquiring some risk factors conditioning the evolution of it. One hundred children, aged from 16.6 to 53.4 months, suffering from moderate to severe recurrent asthmatic bronchitis, have been checked at the follow-up at the Broncopneumologic and Allergic Pediatric Unit of the SS Annunziata Hospital (Naples). Among the 100 children checked, 25 have been dropped at the follow-up; the difference between the sample checked and the one dropped at the follow-up is not statistically relevant. Four are variables examined: age, allergic medical history, number of asthma episodes, breast feeding, association or not of atopic dermatitis. The evolution of the symptomatology has not been propitious, as, at the end of three years of analysis, 73.3% of the 5-year-old patients had still persistent asthma. The risk factors of asthma recurrence are: parents smoking habits with a relative risk of 18 times more in patients with disadvantageous evolution (R.R. = 18) and at a less measure the overcrowding of the bedroom (R.R. = 1.5). The age at the onset in of the symptomatology, the positive familiar medical history for allergic illness, the breast feeding and the atopic dermatitis have not resulted statistically different between the group with advantageous evolution and the one with disadvantageous outcome. Passive smoking is a very disadvantageous prognostic factor; it may contribute to the disadvantageous evolution of the moderate to severe asthmatic bronchitis in the early childhood towards the recurrent or chronic bronchial asthma of the late childhood.