This study deals with comparative investigation of the protective effects of disodium cromoglycate (DSCG, Lomudal, Intal) and beclomethasone dipropionate aerosol (BDA, Aldecin, Becotide, Beclovent) on 103 immediate asthmatic responses (IARs) to allergen challenge recorded in 103 patients with an allergic bronchial asthma. Disodium cromoglycate demonstrated highly significant protective effects on the IAR in patients investigated (P less than .01). The protective effects of BDA on the IAR were found to be non-significant (P greater than .01). It is suggested that DSCG should be the first choice in controlling allergic bronchial asthma when the immediate asthmatic response to allergen plays the predominant role.