Massachusetts law defines marital property broadly, and your 401k retirement account is likely a marital asset, to the extent it accrued during your marriage.  Talk to your attorney about your specific situation.

Even if your 401 is marital property, however, that does not necessarily mean that your husband will get half or any part of it.  Massachusetts General Laws Chapter 208, Section 34 envisions an equitable (not necessarily equal) division of marital assets.  There are no set guidelines that judges must follow when awarding assets to the individual parties. Under Section 34, the court will consider such factors as:

The length of the marriage, the conduct of the parties during the marriage, the age, health, station, occupation, amount and sources of income, vocational skills, employability, estate, liabilities and needs of each of the parties and the opportunity of each for future acquisition of capital assets and income.

Good luck, and for more information, follow this link to our post about 401 K plans and divorce in Massachusetts.