He returned to Singapore and pioneered the development of Vascular Surgery as a specialty in this country. In 1990, he was the first to be awarded the Singapore Government's Higher Manpower Development Scholarship for Vascular Surgery. He was sent for training in this specialty to Sydney, Australia, where he did a Fellowship in Vascular Surgery at the St. Vincent's Hospital.

Since then, Dr. Nawaz has done extensive work in the field of Vascular Surgery, and has developed a special interest in the treatment of varicose veins and related problems. He has written and lectured widely on this topic. He is an active member of the International Society of Cardio-Vascular Surgeons and the Singapore Vascular Society.

Dr. Nawaz set up his private practice in 1995. He has introduced many newer techniques and technologies to further the treatment of venous disorders locally, including being the first to introduce and use endovenous laser therapy in the region.