At which hospitals are the nurses striking? The open-ended strike started Monday at United Hospital in St. Paul, Mercy Hospital in Coon Rapids, Unity Hospital in Fridley, the Phillips Eye Institute in Minneapolis, and Abbott Northwestern.

What services are affected? While essential services will continue at all of the hospitals, some specialty services such as water births might be shelved. Tours and prenatal classes for expectant mothers have been canceled at Abbott.

What are the staffing levels during the strike? Allina chief executive Penny Wheeler said the 1,500 temporary nurses recruited from across the country should be enough to maintain normal operations at the hospitals because the replacements will work full time, while two-thirds of the regulars are part time. About 350 of the 4,800 union nurses have said they will cross picket lines.

Will the strike affect patient care? Allina officials say it won't and that it didn't in June when nurses at the five hospitals walked out for a week. The union disputes that.

What's the main dispute? Health insurance. In a move Allina estimates would save $10 million a year, it wanted to switch nurses from their union-only health plans to ones that cover all other Allina employees, meaning nurses would pay lower premiums but have higher deductibles and out-of-pocket expenses. Allina has since altered its position, offering to let the nurses keep their two most popular plans. But the union says that's a step backward.

What's the status of the negotiations? The two sides met Friday with federal mediators. The 22-hour talks broke off early Saturday with no agreement on a new three-year contract, and no new talks scheduled. The contract expired June 1.