SC 13G: Schedule filed to report acquisition of beneficial ownership of 5% or more of a class of equity securities by passive investors and certain institutions

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

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SCHEDULE 13G
(Rule 13d-102)

INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT
TO RULE 13d-1(b)(c), AND (d) AND AMENDMENTS THERETO FILED
PURSUANT TO RULE 13d-2(b)

(Amendment No. __)(1)

Resmed, Inc.
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(Name of Issuer)

Common
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(Title of Class of Securities)

761152107
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(CUSIP Number)

December 31, 1999
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(Date of Event which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which
this Schedule is filed:

|x_| Rule 13d-1 (b)
|_| Rule 13d-1 (c)
|_| Rule 13d-1 (d)

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(1) The remainder of this cover page shall be filled out for a reporting
person's initial filing on this form with respect to the subject class of
securities, and for any subsequent amendment containing information which would
alter disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be
deemed to be "filed" for the purpose of Section 18 of the Securities Exchange
Act of 1934 ("Act") or otherwise subject to the liabilities of that section of
the Act but shall be subject to all other provisions of the Act (however, see
the Notes).

CUSIP No. SCHEDULE 13G Page _ of __ Pages
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1 NAME OF REPORTING PERSONS
I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY)
William Blair & Company, L.L.C.
36-2214610
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2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
(a) |_|
(b) |_|
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3 SEC USE ONLY


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4 CITIZENSHIP OR PLACE OF ORGANIZATION

Chicago, Illinois USA
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5 SOLE VOTING POWER

286,850
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NUMBER OF 6 SHARED VOTING POWER
SHARES
BENEFICIALLY
OWNED BY --------------------------------------------------------------
EACH 7 SOLE DISPOSITIVE POWER
REPORTING
PERSON 1,436,404
WITH --------------------------------------------------------------
8 SHARED DISPOSITIVE POWER


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9 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

1,436,404
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10 CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES
CERTAIN SHARES*

|_|
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11 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

9.6%
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12 TYPE OF REPORTING PERSON*

BD, IA
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*SEE INSTRUCTIONS BEFORE FILLING OUT!