Stockholders Agreement

STOCKHOLDERS AGREEMENT
UNILAB CORPORATION
Dated as of November 23, 1999

TABLE OF CONTENTS

ARTICLE I RESTRICTIONS ON TRANSFER OF COMMON STOCK.............................. 2

ARTICLE II RIGHTS OF MANAGEMENT TO SELL.......................................... 4

ARTICLE III PURCHASES BY THE COMPANY............................................... 7

ARTICLE IV PURCHASE PRICE.......................................................... 10

ARTICLE V PROHIBITION ON PURCHASES................................................ 13

ARTICLE VI SALES TO THIRD PARTIES................................................. 15

ARTICLE VII REGISTRATION RIGHTS................................................... 22

ARTICLE VIII CHARTER DOCUMENTS AND BOARD OF DIRECTORS............................. 26

ARTICLE IX TERMINATION............................................................ 29

ARTICLE X MISCELLANEOUS PROVISIONS............................................... 30

STOCKHOLDERS AGREEMENT

STOCKHOLDERS AGREEMENT, dated as of November 23, 1999, among UNILAB CORPORATION, a Delaware corporation (the "Company"), and the stockholders and optionholders listed herein.

This agreement sets forth restrictions on transfer, rights of first refusal, registration rights, board voting arrangements, and related provisions concerning Common Stock of the Company.

PARTIES

Company Name:

Date:

Third Party Investor / Stockholder Name:

Entity Type:

ARTICLE I - RESTRICTIONS ON TRANSFER OF COMMON STOCK

1.1 General Restriction on Transfer by Stockholders. Prior to an IPO, shares of Common Stock may not be transferred except as permitted by this Agreement.

1.2 Permitted Transferees.

Management Stockholder transfer to trust/family entity:

Transfer by will / intestate succession:

Transfer with prior written consent of Board and Kelso:

Third Party Investor charitable transfer (up to 25%):

ARTICLE II - RIGHTS OF MANAGEMENT TO SELL

2.1 Management Stockholders' Right to Sell. A Management Stockholder may sell all shares to the Company under certain termination events.

Termination due to Retirement:

Termination due to Death:

Termination due to Disability:

Termination without Cause:

Resignation for Good Reason:

Number of shares to be sold:

Notice date:

Fair Market Value:

Carrying Value:

ARTICLE III - PURCHASES BY THE COMPANY

3.1 Right to Purchase Shares from Management Stockholders. The Company may purchase shares upon certain termination events.

Termination for Cause:

Termination without Cause:

Resignation for Good Reason:

Retirement:

Death or Disability:

ARTICLE IV - PURCHASE PRICE

4.1 Fair Market Value. Appraisal may be required to determine fair market value of Common Stock.

Appraisal Date:

Appraiser Name:

Fair Market Value Determination:

ARTICLE V - PROHIBITION ON PURCHASES

5.1 Prohibited Purchases. The Company shall not be obligated to purchase shares if prohibited by law or debt agreements.

Maximum Amount Restriction Applies:

ARTICLE VI - SALES TO THIRD PARTIES

6.2 Right of First Refusal. An offering stockholder must give notice before selling to a third party.

Third Party Buyer Name:

Offer Price Per Share:

Offer Notice Date:

Tag-Along Notice:

Drag-Along Notice:

Involuntary Transfer:

Involuntary Transfer Description:

ARTICLE VII - REGISTRATION RIGHTS

7.1 Demand Registration. Kelso may request registration of shares.

Demand Registration Requested:

Piggyback Registration Requested:

Underwriter Name:

Holdback Period:

ARTICLE VIII - CHARTER DOCUMENTS AND BOARD OF DIRECTORS

8.2 Board of Directors. The Board will be formed as described in the agreement.

CEO Is a Board Member:

Nominee Name:

Replacement Nominee:

ARTICLE IX - TERMINATION

9.1 Cessation of Ownership of Common Stock. A party ceases to be bound when it no longer owns Common Stock.

Termination Upon IPO:

Termination Date:

ARTICLE X - MISCELLANEOUS PROVISIONS

10.1 Stock Certificate Legend. Certificates must bear the required legend until removal is appropriate.

Legend Removal Requested:

Governing Law:

Notice Address:

SIGNATURES

ACKNOWLEDGMENT / ATTACHMENT SIGNATURE LINE

The undersigned becomes a party to the Stockholders Agreement as a Management Stockholder.

Signature:

Print Name:

Date: