He was a brilliant scholar and gained Distinction in Anatomy in the 2nd Professional Examination, an honour he shared with his classmate Quek Eng Lan (whom he subsequently married on 22 August 1938).

In the Final examination in 1938, Swee Aun obtained Distinction in Medicine and Materia Medica and was awarded the much coveted Lim Boon Keng Medal.

Lim Swee Aun stayed on in Taiping Hospital and evacuated with the Medical Convoy by stages going southwards as the enemy approached from the north.

Dr. Lim Swee Aun, Dr. Tan Cheng Leng and the Parsi Jal Manecksha also secretly helped the Indian Prisoners of War of the Motor Transport Unit No.

After the Japanese surrender on 2 September 1945, Lim Swee Aun resigned from Dr. Tan Chen Leng's employment and started his own practice at 75 Kota Road, Taiping, Perak.

He worked hard, day and night attending to his sick patients and doing house calls even though the country was in a state of Malayan Emergency from the communist activities.

On his way to the General Agreement on Tariffs and Trade Conference (GATT) Geneva that year, Dr. Lim confirmed that his ministry had received many inquiries from foreign and local firms regarding the possibility of setting up vehicle manufacturing factories in the Federation.

A Malayan delegation departed for London on 25 June 1963 and was led by Tun Abdul Razak, Tan Siew Sin and Dr Lim Swee Aun (Minister for Commerce).

[3] The function of Mr. Tan and Dr. Lim was in Sir Geofroy Tory's view, to restrain Tun Razak from making undue concessions.

[5] Syed Jaafar Albar participated in verbal duels with the Singaporean Prime Minister, Lee Kuan Yew, over the issue of ketuanan Melayu (Malay sovereignty over Malaysia), accusing Lee and some other Chinese Malaysians—referring to them as kaum pendatang or immigrants—of being lodgers (orang tumpangan), abusing the hospitality of the Malays who were the "masters of the house".

"[6][7] Prime Minister Lee Kuan Yew in his speech at the Malaysia Solidarity Convention on 6 June 1965 congratulated Lim Swee Aun for his courage in saying it.