This study reports a family comprising four generations in whom nephritis, deafness, congenital cataracts, macrothrombocytopenia, and leukocyte inclusions were observed in varying combinations in eight of 17 members. The family differs from others reported in that their hematologic abnormalities include not only macrothrombocytopenia, but also small, pale blue cytoplasmic inclusions in the neutrophils and eosinophils. Light microscopic appearance of the inclusions resembled that of toxic Dohle bodies and inclusions of May-Hegglin anomaly, but their ultrastructural appearance was unique. The inclusions consisted of clusters of ribosomes and small segments of rough endoplasmic reticulum (RER). They lacked the parallel 10-nm filaments characteristic of May-Hegglin anomaly and the parallel strands of RER seen in toxic Dohle bodies. Platelets were large, but their light and ultrastructural appearance was not significantly different from normal platelets. Platelet aggregation in response to epinephrine, arachidonate, thrombin, adenosine diphosphate, collagen, and ristocetin was normal. Levels of nucleotides and serotonin were elevated in proportion to cell volume. The concentration of adenosine triphosphate secreted and the percentage of arachidonic acid converted to thromboxane B2 were proportional to cell number. Deafness was high-tone sensorineural. Renal disease ranged from microscopic hematuria to end- stage renal failure necessitating dialysis and kidney transplantation. All affected adults had cataracts. This family represents a variant of Alport's syndrome with cataracts and leukocyte inclusions that, because of the associated macrothrombocytopenia, may be confused with May- Hegglin anomaly.