A general practitioner survey was carried out to compare the efficacy of doxycycline and amoxycillin in the treatment of 267 patients with respiratory tract infections requiring antibiotic therapy. The findings, based on clinical observations, suggest that both antibiotics were equally effective in providing prompt improvement and complete resolution of the infection, only 7 of the 134 receiving doxycycline and 13 of the 133 patients receiving amoxycillin failing to show a satisfactory response. There was a statistically significant better response in those patients with acute and acute-on-chronic bronchitis who were treated with doxycycline. It is possible that this may have been related to a local upsurge in mycoplasma infection at the time of the study.