The invention provides a pharmaceutical composition comprising at least one polypeptide of the following (a) to (d): (a) a polypeptide comprising the amino acid sequence of SEQ ID NO:1； (b) a polypeptide comprising an amino acid sequence comprising one or more amino acid deletions, insertions, substitutions or additions in the amino acid sequence of the above (a) and having a platelet aggregation inhibitory activity and/or a platelet adhesion inhibitory activity； (c) a polypeptide comprising the amino acid sequence of SEQ ID NO:3； and (d) a polypeptide comprising an amino acid sequence comprising one or more amino acid deletions, insertions, substitutions or additions in the amino acid sequence of the above (c) and having a platelet aggregation inhibitory activity and/or a platelet adhesion inhibitory activity, as an active component.本發明提供一種藥學組成物，其包含有作為一有效組分的至少一種下列(a)至(d)之多肽：(a)一多肽，它包含有序列辨識編號：1的胺基酸序列；(b)一多肽，它包含有一胺基酸序列包含一個或多個胺基酸刪除、插入、取代或加入位於上述(a)之胺基酸序列內並且具有一血小板凝集抑制活性和/或一血小板黏附抑制活性；(c)一多肽，它包含有序列辨識編號：3的胺基酸序列；以及(d)一多肽，它包含有一胺基酸序列包含一個或多個胺基酸刪除、插入、取代或加入位於上述(c)之胺基酸序列內並且具有一血小板凝集抑制活性和/或一血小板黏附抑制活性。
