Splenic atrophy is an uncommon diagnosis associated with celiac sprue or other well-characterized connective tissue diseases, drepanocytosis, or amyloidosis. We report two patients with splenic atrophy revealed by thrombocytosis. Both patients had anti-nuclear antibodies. Patient 1 also had a grade III Chisholm lymphocytic sialadenitis with a rheumatoid factor, anti-extractable nuclear antibodies, and a polyclonal hypergammaglobulinemia consistent with the diagnosis of Sjögren's syndrome. Patient 2 displayed a previous history of idiopathic pericarditis. An anti-pneumococcal vaccination was given to both patients and neither experienced infectious complications. Splenic atrophy should be suspected in patients with thrombocytosis of unexplained origin and a blood smear consistent with asplenia. Such patients must be checked for clinical and biological symptoms of autoimmune disorders.