After London, Balfour travelled to France in 1657 where he studied medicine in Paris and at the University of Caen.
Balfour obtained a degree with a dissertation entitled De Venae Sectione in Dysenteria.
By this time, he had amassed a large collection of scientific and medical books, curiosities and instruments: his 'rarities' were called the 'Museaum Balfourianum' by contemporaries.
Balfour's cousin was Robert Sibbald, whom he succeeded as third president of the Royal College of Physicians of Edinburgh in 1684.
[5] Travel advice to Patrick Murray, Laird of Livingstone (who had died on European tour in 1671) was subsequently published as Letters to a Friend (1700).