[LATHAM & WATKINS LETTERHEAD]




                                November __, 1999


                                                                     EXHIBIT 5.1

MidAmerican Funding, LLC
666 Grand Avenue
Des Moines, Iowa 50303

                  Re:      Registration Statement on Form S-4;
                           $700,000,000 Aggregate Principal
                           Amount of Senior Secured Notes and Bonds

Ladies and Gentlemen:

                  In connection with the registration of (i) $200,000,000 5.85%
Senior Secured Exchange Notes due 2001 (the "2001 Securities"), (ii) $175,000,00
6.339% Senior Secured Exchange Notes due 2009 (the "2009 Securities") and (iii)
$325,000,000 6.927% Senior Secured Exchange Bonds due 2029 (the "2029
Securities" and, collectively with the 2001 Securities and the 2009 Securities,
the "Securities") by MidAmerican Funding, LLC, an Iowa limited liability company
(the "Registrant"), under the Securities Act of 1933, as amended, on Form S-4
filed with the Securities and Exchange Commission (the "Commission") on November
__, 1999 the "Registration Statement"), you have requested our opinion with
respect to the matters set forth below.

                  In our capacity as your special counsel, we have made such
legal and factual examinations and inquiries as we have deemed necessary or
appropriate for purposes of this opinion.

                  In our examination, we have assumed the genuineness of all
signatures, the authenticity of all documents submitted to us as originals, and
the conformity to authentic original documents of all documents submitted to us
as copies. As to facts material to the opinions, statements and assumptions
expressed herein, we have, with your consent, relied upon


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oral or written statements and representations of officers and other
representatives of the Registrant and others.

                  We are opining herein as to the effect on the subject
transaction only of the internal laws of the State of New York, including
statutory and reported decisional law thereunder, and we express no opinion with
respect to the applicability thereto, or the effect thereon, of the laws of any
other jurisdiction or as to any matters of municipal law or the laws of any
local agencies within any state.

                  Capitalized terms used herein without definition have the
meanings assigned to them in the Registration Statement.

                  Subject to the foregoing and the other matters set forth
herein, it is our opinion that as of the date hereof:

                  When the Securities have been duly executed, issued,
authenticated and delivered by or on behalf of the Registrant, the Securities
will constitute legally valid and binding obligations of the Registrant,
enforceable against the Registrant in accordance with their terms.

                  The opinions rendered in the preceding paragraph relating to
the enforceability of the Securities are subject to the following exceptions,
limitations and qualifications: (i) the effect of bankruptcy, insolvency,
reorganization, moratorium or other similar laws now or hereafter in effect
relating to or affecting the rights and remedies of creditors; and (ii) the
effect of general principles of equity, whether enforcement is considered in a
proceeding in equity or law, and the discretion of the court before which any
proceeding therefor may be brought.

                  We have not been requested to express, and with your knowledge
and consent do not render, any opinion as to the applicability to the
obligations of the Registrant under the Indenture and the Securities of Section
548 of the United States Bankruptcy Code or applicable state law (including,
without limitation, Article 10 of the New York Debtor and Creditor Law) relating
to fraudulent transfers and obligations.

                  To the extent that the obligations of the Registrant under the
Indenture may be dependent upon such matters, we assume for purposes of this
opinion that: (i) each of the Registrant and the Trustee (a) is duly organized,
validly existing and in good standing under the laws of its jurisdiction of
organization, (b) has the requisite organizational and legal power and authority
to perform its obligations under the Indenture and the Securities, (c) is duly
qualified to engage in the activities contemplated by the Indenture and (d) has
duly authorized, executed and delivered the Indenture; (ii) the Securities have
been duly authorized by all necessary limited liability company action of the
Registrant; (iii) the Indenture is the legally valid, binding and enforceable
obligation of the Trustee, enforceable against the Trustee in accordance with
its terms; and (iv) the Trustee is in compliance, generally and with respect to
acting as a trustee under the Indenture, with all applicable laws and
regulations. We have also assumed, with your

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consent, that the choice of law provisions in the Indenture would be enforced by
any court in which enforcement thereof might be sought.

                  We consent to your filing this opinion as an exhibit to the
Registration Statement and to the reference to our firm contained under the
heading "Legal Matters" in the Prospectus.




                                             Very truly yours,