1 Exhibit 23.1 SCHEDULE II IDEC PHARMACEUTICALS CORPORATION AND SUBSIDIARY VALUATION AND QUALIFYING ACCOUNTS (In thousands) Years Ended December 31, 1998, 1997 and 1996 Additions ---------------------------------- Balance Charged to Charged to Balance beginning costs and other at End Description of year expenses accounts Deductions of Year - ----------- --------- ---------- ---------- ---------- -------- Year ended December 31, 1998 Inventory reserve $ 2,082 $ 3,402 $ -- $(3,630) $ 1,854 Allowance for contract revenue receivables 51 724 -- -- 775 ------- ------- ------- ------- ------- $ 2,133 $ 4,126 $ -- $(3,630) $ 2,629 ======= ======= ======= ======= ======= Year ended December 31, 1997 Inventory reserve $ -- $ 2,082 $ -- $ -- $ 2,082 Allowance for contract revenue receivables 1,681 -- -- (1,630) 51 ------- ------- ------- ------- ------- $ 1,681 $ 2,082 $ -- $(1,630) $ 2,133 ======= ======= ======= ======= ======= Year ended December 31, 1996 Allowance for contract revenue receivables $ 658 $ -- $ 1,423 $ (400) $ 1,681 ------- ------- ------- ------- ------- $ 658 $ -- $ 1,423 $ (400) $ 1,681 ======= ======= ======= ======= =======