The development and implementation of quality referral systems reflects sound national health planning. This review appraised the data on referral systems, in particular psychiatric referrals, with special reference to Saudi Arabia. A computer search was made of relevant literature in the past 2 decades. The rate and process of referring patients through referral letters varies globally across practice settings and is initiated by an array of factors linked with health consumers, health providers and delivery systems. Referral systems, including consultation–liaison services, are an essential component of any health care organization for offering a complete range of good quality, specialized health services.