A double-blind multicenter study comparing the effect of placenta eluted IgG and venoglobulins in the treatment of rheumatoid arthritis was conducted in 113 hospitalized patients. Rheumatoid arthritis was severe, classical (92 cases) or definite (21 cases), seropositive in 87 cases, with nodules in 32 cases; the mean duration of the disease was 10 years. The majority of patients had previously received numerous slow-acting drugs without result or with side-effects. A statistically significant decrease of all the quantitative indices but one (grip strength) was obtained with both products on the 8th day of treatment; the effect of placenta eluted IgG was statistically superior for the number of swollen joints (P less than 0.025), Ritchie's index (P less than 0.0005) and some extra-articular manifestations. There was no significant decrease in associated treatments and biological parameters (erythrocyte sedimentation rate, rheumatoid factor). Tolerance was excellent; some cases of benign venulitis were observed; treatment was never discontinued on account of side-effects. Further placebo-controlled of each of these immunoglobulins of placental origin are needed for firm conclusions to be drawn.