The fonds largely document Dr. Segall's professional activities as a cardiologist. It contains correspondence, notes, experimental notebooks, lecture notes, articles, speeches, patients' records, electrocardiograms, reprints and material pertaining to the Louis Gross Memorial Lectures, 1922-1979. Also included are several electrocardiograph machines, dictation devices, and audio recordings (reel-to-reel tapes, dictation disks, and cassette tapes). In addition, the fonds contain records of Dr. Segall's personal and family correspondence, financial transactions, and various other official and unofficial documents.