Apart from the contribution, no. Upon commencing work in Belgium, all foreign nationals must join the state Belgian health insurance scheme or present evidence of private health insurance in Belgium (the same applies to the self-employed in Belgium). All the mutuelle providers offer more or less the same services, hence employers often enrol you in one automatically. You should clarify this with your employer as soon as possible, as you may wish to choose your own mutuelle, particularly if you wish to register with one that is affiliated to your particular religious or political views, or if you find a mutuelle that offers certain useful services, such as English-language services.
Registering with a Belgian health insurance company usually requires you to present a copy of your passport or ID card.