Chlamydophila (Chlamydia) pneumoniae is associated with asthma and several other respiratory illnesses. Disodium cromoglycate (DSCG) is known to inhibit both immediate and late asthmatic responses. In this study, the inhibitory effect of DSCG on the growth of C. pneumoniae was examined by minimum inhibitory concentration (MIC) and pre-inoculation minimal cidal concentration (MCC) assays using HL cells and C. pneumoniae AR-39. DSCG below the clinically relevant concentration inhibited the growth of C. pneumoniae in a dose-dependent manner in both the MCC and MIC assays. The inhibitory effect was also time-dependent in the MCC assay at 20 mg/ml of DSCG. These results warrant further clinical study on the connection between C. pneumoniae infections and use of DSCG.