Pedro María Sison y Macasieb (January 18, 1885–June 12, 1938) was a senator of the Philippines, judge of the Court of First Instance, a statesman and philanthropist. He was a delegate to the Philippine Constitutional Convention of 1935. ^[1]

Sison was born in Urdaneta, Pangasinan on January 18, 1885. His father was Pedro Sison Jr., and his mother was Eusebia Macasieb.

In 1896, at the age of 11, Sison joined his father in fighting the Spaniards during the Philippine Revolution. During the American colonial period, he helped his father restore peace and order in Binalonan and Urdaneta towns.^[2]

In 1912, at the age of 27, Sison was elected to the Philippine Assembly, representing Pangasinan's 4th district. Four years later, he was elected to the Philippine Senate. Representing the Second Senatorial District of La Union, Pangasinan, and Zambales, Sison served as a senator during the Fourth and Fifth Legislature from 1916 to 1922 and whose Senate president was Manuel L. Quezon.^[3]

Together with Rafael Palma, Sison sponsored in 1916 a bill on women's suffrage that was approved by the Senate. It was the first time that such bill was sponsored.^[4]

On February 28, 1929, he was appointed as an auxiliary judge. The following year, he was promoted as judge of Court of First Instance.^[5]

In 1934, he was elected as a delegate to the 1935 Philippine Constitutional Convention.

He married Gracia Palisoc Moran, and had nine children.

Sison died on June 12, 1938.^[2]