Introduction Libman–Sacks endocarditis is a rare cardiac manifestation of systemic lupus erythematosus, in which there is sterile vegetation in the heart valves with a significant risk of infective endocarditis. Description Patient aged 29, presents with a deep nephrotic syndrome, associated with microscopic hematuria, we find in his history a notion of inflammatory arthritis of the ankles, wrists and knees, with alteration of the general state in a long-term febrile context, associated with a chronic inflammatory left subpalpebral cellulitis. The patient was in average general condition, asthenic, with exertional dyspnoea, oedema of the lower limbs rising to the legs and the cardiac examination found a significant murmur at the aorto-mitral focus. Biologically: a deep nephrotic syndrome was found. Inflammatory syndrome with PRC at 80 mg and SR at +++. Inflammatory anaemia and lymphopenia. An echocardiography done, finds a mitro-aortic valve thickening, with the presence of fine vegetations on the aortic side of the posterior sigmoid, in addition to an important mitral and aortic leak. The immunological work-up was strongly positive for antiphospholipid syndrome with IgG anti-cardiolipin antibodies (+), IgG anti-B2GP1 antibodies (+), antinuclear factor antibodies (+) with a speckled appearance; a renal biopsy was performed and was consistent with lupus glomerulonephritis. High-dose corticosteroids combined with double antibiotic therapy significantly improved the patient's clinical and biological parameters. Conclusion Our observation is quite exceptional because cardiac involvement usually occurs years after the onset of SLE, but in this observation the onset is quite nasty, first in a male subject, associating renal involvement, endocarditis and SAPL. Treatment was based on a combination of antibiotics, corticoids and synthetic antimalarials.