The authors report 4 cases of toxoplasmosis in patients with acute disseminated lupus erythematosus (ADLE). In one case, a pregnant patient with serology indicative of chronic infection, infected the neonate who died of subacute toxoplasmosis. Although ADLE is a classical cause of immunodepression, toxoplasmosis is a rare complication; only 5 cases were found in a review of the literature. Toxoplasmosis infection may resemble an exacerbation of lupus; an accurate diagnosis is essential as the treatment of the two conditions is radically different. The problems of diagnosis of toxoplasmosis in immunodepressed patients are reviewed and the therapeutic approach, especially in pregnant patients, is discussed. In ADLE, the authors recommend checking toxoplasmosis serology before starting and during treatment with corticosteroids. Special attention should be paid to pregnant women with apparently chronic serological changes as neonatal infection may occur.