This report describes some of the properties of a clinical-grade preparation of human growth hormone (hGH) extracted from acetone-preserved autopsy human pituitary glands and used in Great Britain from 1967 to 1980. Gel filtration of this hGH on Sephadex G-100 yielded (on a weight basis) an average of 48% of a high molecular weight fraction, 10% of an intermediate fraction expected to contain dimeric forms of the hormone and 33% of a fraction considered to be the hGH monomer. The immunoassay potency of the monomer fraction was twice that of the clinical-grade preparation and the amino-acid composition of the monomer fraction agreed well with that obtained from published hGH sequence data. The results of polyacrylamide-gel electrophoresis (under reducing and dissociating conditions) and amino-acid analysis of the high molecular weight fraction suggest that it contains around 30% of aggregated hGH as well as other material not separated from hGH by the purification procedure.