Hajar is married to Rachel Querubin, a cardiologist from the Philippines whom he met during training in the USA. Rachel was Director of Non-invasive Cardiology in HMC, Doha, Qatar from 1981 to 2014, founder and editor-in-chief of Heart Views and currently senior consultant cardiologist as well as Director of HH Publications and Executive Coordinator for Research, Heart Hospital, HMC, Doha, Qatar. They have five children.[8]