We tested the hypothesis that health insurance premium costs per employee are lower for employee groups where multiple health plans are offered and the employer pays a level dollar amount of the chosen premium than for employee groups where these two conditions are not met. Proposed national legislation relies on these conditions to create a competitive health care market. Data on 56 employee groups in 1981 and 66 employee groups in 1982 were collected from two surveys of large employers in Minnesota. Regression analysis of premium data from both surveys rejected the hypothesis. Indemnity plans in multiplan groups were cheaper if the employer paid a level dollar contribution versus a level percent (including 100) contribution. However, groups offered only an indemnity plan had lower premiums than groups meeting the two legislative conditions. These findings apply to both individual and family coverage premiums and are not caused by systematic differences in benefit provisions, employee demographics or factors influencing loading charges. Our findings cast doubt on attempts to achieve health care competition by legislative changes in insurance options and contribution methods.