They are taking place in NHS Fife and NHS Dumfries and Galloway.
Health secretary Nicola Sturgeon said: ‘We want an NHS that is truly mutual, where patients are not just partners in their own care but where local communities are at the heart of local decision-making.
‘Difficult decisions will no doubt still have to be taken but with this kind of guaranteed voice, these pilots will ensure decisions are taken with the full involvement of local people as co-owners of the NHS.'
NHS Fife is electing 13 of the 25 positions on its board, with NHS Dumfries and Galloway doing so with 11 of 21 (10 members of the public and one local authority member). Ballot papers will be issued 8-13 May, closing on 10 June with the results available later that day.
People aged 16 and 17 will have the right to both vote and stand.
Theresa Fyffe, director of RCN Scotland, said: ‘The Scottish government must not lose sight of the fact that the purpose of piloting health board elections is to establish if this improves public involvement with health board decision-making.'