Previous studies have shown that left ventricular (LV) diastolic function is frequently impaired in patients with systemic lupus erythematosus. We prospectively studied echo-Doppler indices of LV diastolic function in 18 patients with primary antiphospholipid syndrome (PAPS), who where compared to a group of 18 healthy controls. Heretofore undescribed LV relaxation abnormalities were found in the PAPS group: this finding suggests the existence of a causal link.