Exhibit 8.1

Organizational Structure

At December 31, 2006, we had the following principal subsidiary undertakings:

		Group
		Share		Registered Office &
Company	Nature of Business	%		Country of Incorporation Operation
Athena Neurosciences, Inc.	Holding company		100	800 Gateway Blvd South San Francisco, CA, United States
Elan Capital Corp., Ltd.	Financial services company		100	Clarendon House 2 Church St Hamilton, Bermuda
Elan Drug Delivery, Inc.	R&D		100	3000 Horizon Drive King of Prussia, PA, United States
Elan Finance plc	Financial services company		100	Treasury Building, Lower Grand Canal Street, Dublin 2, Ireland
Elan Holdings, Inc.	Manufacture pharmaceutical and medical device products		100	1300 Gould Drive Gainesville, GA, United States
Elan Holdings Ltd.	Holding company		100	Monksland, Athlone Co. Westmeath, Ireland
Elan International Services Ltd.	Financial services company		100	Clarendon House, 2 Church St Hamilton, Bermuda
Elan Management Ltd.	Provision of management services		100	Treasury Building, Lower Grand Canal Street, Dublin 2, Ireland
Elan Pharma International Ltd.	R&D, manufacture, sale and distribution of pharmaceutical products and financial services		100	Monksland, Athlone Co. Westmeath, Ireland
Elan Pharmaceuticals, Inc.	R&D and sale of pharmaceutical products		100	800 Gateway Blvd South San Francisco, CA, United States
Monksland Holding BV	Financial services company		100	Amsteldijk 166 6th Floor 1079 LH Amsterdam The Netherlands
Neuralab Ltd.	Non-trading		100	Clarendon House, 2 Church St Hamilton, Bermuda