An automated high performance liquid chromatographic method with remote controlled column switching was used to measure the concentration of spiramycin in pelvic tissues and plasma after oral administration of the antibiotic. Three oral doses of 2 g spiramycin were given to patients scheduled for elective gynaecological surgery over the 14 h before 6 a.m. on the day of surgery. Spiramycin concentrations in serum ranged from 7.4 to 12.5 mg/l between 3 h 20 min and 9 h 20 min after the last dose of spiramycin. Spiramycin pelvic tissue concentrations were determined in five of the eleven females and ranged from 4.4 to 33.3 mg/kg. The highest concentrations were observed in the Fallopian tube. These preliminary results suggest that spiramycin has good diffusion into female pelvic tissues.