Prof. Prematilleke  has achieved fame as a museologist, through his planning and organization of Archaeological, Art, and Irrigation Museums , all of which are of international standard, and some are unique institutions established for the first time anywhere in the world.

• The teaching museum of the Department of Archaeology, was begun a couple of years after the foundation of the department under the headship of Prof. Paranavitana.
• Prof. Paranavitana retired at the end of 1964 and Prematilleke who took over,  further developed the museum 
• The museum contains some unique artifacts and antiquities like the gold stylus of King Narendrasimha, Carve Ivories, Intaglios of West Asiatic, Indian and Sri Lankan origin, coins & beads etc.
• The museum was renamed “Senarat Paranavitana Teaching and Research Museum” in 1998, which was declared open by Prof Prematilleke.
• The museum consists largely of the bequest of Leslies de Saram, one of the most enthusiastic and well known collectors of the time. Other collections of W.H.Biddel and D.P.E.Hettiarachchi too enriched the museum artifacts. Plaster casts of ancient sculpture, both Buddhist and Hindu, were prepared by J.D.A.Perera, the then principal of the Ceylon Technical College.In later times, other teaching material belonging to Pre and Protohistoric phases too have been added to the collection. Thus, the artifacts exhibited in the Museum  consists of figure sculptures, ritual objects, decorative carvings, weapons and tools, writing equipment including epigraphs, personal and household  effects, medical and surgical equipment, costumes and painted cloths, coins and medals, intaglios, beads, geological material, etc
• In 2004 he published a comprehensive catalogue of objects in the museum
• Some of the objects of significance were exhibited in local and foreign exhibitions including the Commonwealth Institute, London