Mies Deinum was born in Semarang, Indonesia, but received her education at the Kunstnijverheidsschool in Haarlem, The Netherlands. She became a painter, studying with the famous Dutch painter Lizzy Ansingh, among others. She took courses in illustration from B. Midderigh-Bokhorst and Herman Moerkerk.
At the end of the thirties, she worked for two years for the publisher De Spaarnestad, making illustrations for children's magazines. She created three newspaper strips: 'Sambo de Olifant', 'Dieren-jamboree' (with text by RUP) and 'Myra het Elfje'. All of these have been reprinted in color book format by publisher Pax Holland in Amsterdam.