All patients diagnosed of brucellosis in 4 regional hospitals during a period of nine years were reviewed, in an attempt to evaluate the efficacy of different antimicrobic regimens and also the clinical features. Evolution and complications of brucellar sacroiliitis. Of a total of 548 patients, 12% had been diagnosed of sacroiliitis and, of theme, 49 had complete data available with efficacy of different treatments, the time elapsed until fever and pain ceased was evaluated, together with initial therapeutic failures, relapses and length of hospital stay. Brucellar sacroiliitis is the most frequent osteoarthral complication of Brucella sp. in our setting. Keeping an stable incidence. It is predominant among young male (82%) population (mean age 25 +/- 12 years). The illness evolution is acute and less frequently subacute with a evolution mean-time before referral of 38 +/- 44 days (minimum 4 days, maximum 180 days). Fever (81%) and pain on gluteus and low lumbar localizations (100%) are the more frequent clinical features. Time elapsed until pain ceased was longer with doxycycline plus rifampicin (68 +/- 86) than with doxycycline plus streptomycin (28 +/- 43) (less than 0.05) and length of hospital stay was also longer with said treatment (p less than 0.05). There were no differences concerning time frame until fever ceased, initial therapy failures and relapses. Sequelae are infrequent and consist in persistency of pain. In resume response to treatment with usual regimens, doxycycline plus streptomycin of doxycycline rifampicin is good, being however time elapsed until pain ceases of mean length in hospital stay shorter in the group receiving doxycycline plus streptomycin. Control studies to confirm these data are need.