Margaret Barnet (Barnett) Cruickshank was born on 1 January 1873, the eldest, with her twin sister, of seven children of George Cruickshank, a contractor and farmer, and his wife, Margaret Taggart. During this period the family were living in Hawksbury (later Waikouaiti), Otago, though the twins' place of birth was registered at Palmerston. When Margaret and her twin, Christian (known as Christina), were about 10 years old their mother became ill. To help the family cope the girls alternated attending school. One stayed home to care for the five younger children in the family, and in the evening the other one taught her twin what she had learned at school during the day. Their mother died on 19 June 1883.
After attending Palmerston District High School, Margaret went to Otago Girls' High School, where she was joint dux with her sister and won a New Zealand University Junior Scholarship in 1891. Christina Cruickshank eventually gained an MA and an MSc at the University of Otago and became principal of Wanganui Girls' College. Margaret followed Emily Siedeberg, a friend of hers at school, into the University of Otago Medical School and became the second woman in New Zealand to complete a medical course. She graduated with the degree of Bachelor of Medicine in 1897, one year after Siedeberg.
Margaret Cruickshank then accepted the position of assistant to Dr H. C. Barclay of Waimate, South Canterbury. On 3 May 1897 she became the first New Zealand woman to register as a doctor and subsequently to engage in general medical practice. For the rest of her life, apart from a year's study overseas, Cruickshank worked in Waimate, where she was made a partner in the practice. Her hard work and devotion to her patients won their trust and affection.
Margaret Cruickshank's commitment to her work was shown in her obtaining the degree of Doctor of Medicine at the University of Otago in 1903 and in her study for further qualifications at the Universities of Edinburgh and Dublin in 1913. Before she left New Zealand, the people of Waimate presented her with a purse containing 100 sovereigns and a gold watch and chain. In a farewell speech she was praised for her freedom from pretence, her capacity for loyal friendship, and her gentleness, patience and unselfishness.
After her return from Britain in 1914, Cruickshank's popularity was affirmed when she was chosen as Waimate's candidate in a queen carnival held to raise money during the First World War. An eyewitness described her as 'tall and gracious, in her beautiful court dress of satin and lace, her fair hair with its tints of gold, arranged in a coronal'.
The war was a time of very heavy work for Cruickshank. With Barclay away on active service she had to carry the full burden of the practice and was one of three doctors to share his role as hospital superintendent. In addition she organised the local work of the Waimate Red Cross Fund, to which she had previously given money and time generously. When the terrible influenza epidemic of 1918 struck Waimate Cruickshank was already tired and overworked, but she responded magnificently to the needs of the district. When her driver fell ill she went by bicycle or by horse and gig. She not only gave medical care to her patients but attended to any urgent domestic tasks, which at times included feeding babies and milking cows.
Margaret Cruickshank caught influenza herself and, with her strength already depleted by her labour for her patients, she died of pneumonia at Waimate on 28 November 1918. She had never married. She was one of 14 New Zealand doctors who lost their lives during the epidemic and one of 17 victims who died in Waimate.
The people of Waimate lined the streets as her cortège passed. In gratitude for her work a marble statue of Cruickshank was erected in the town in 1923. On it were carved the words, 'The Beloved Physician / Faithful unto Death.' In 1948 the maternity ward in Waimate Hospital was named in her honour.