The Edinburgh-based agency has won the media planning and buying accounts from fellow Scottish agency Feather Brooksbank for both NHS Scotland and Children 1st.
The NHS account, which is worth in the region of £2m, has switched following the centralisation of government-focused media activity into the Scottish Executive account, which MediaCom Scotland won in 2004.
MediaCom Scotland snapped up the Children 1st brief from Feather Brooksbank after a pitch between the pair and one other unnamed agency.
The six-figure account is to kick off shortly with a new television and cinema campaign.
The third account in the clean sweep for the WPP-owned agency in recent weeks is the £750,000 media planning and buying account for Alliance Trust Savings. The brief was previously handled by Citigate and was picked up by MediaCom Scotland following a competitive pitch.
Euan Jarvie, managing director for MediaCom Scotland, said: "It's been a great summer and it cannot have gone any better."
The string of account wins came as the agency was handed one of the biggest prizes in Scottish commercial circles – Business of the Year for 2005 at last week's Orange-backed National Business Awards.