As already mentioned, the Order of Saint Lazarus was originally created by the militarisation of an order of monks, who as followers of St Basil, had chosen to work amongst those suffering from leprosy. During the time of the crusades all knights who were members of the great military orders found to be suffering from the dreaded leprosy were forced by their own rules to leave their order. As most were warrior monks, and still quite able to fight, they usually joined their confreres fighting under the banner of Saint Lazarus. The early Grand Masters of the Order were themselves amongst those knights so afflicted. These knights, who classed themselves as "living dead", while never large in number, were ferocious in battle, always choosing to die rather than face surrender.

Today the Order is still heavily involved with the relief of leprosy, working in conjunction with other official bodies which have been set up to provide relief for leprosy patients. The World Health Organisation currently estimates that there are fifteen million sufferers today of whom only three and a half million are receiving any form of treatment.

The Order gives aid to leprosy hospitals in Africa, India, South America, the Pacific Islands and Romania. It also supports hospitals in Syria, the Lebanon, Israel, Benin, Malaysia, Turkey and Nepal. It has missions working in Madagascar and in what was known as Biafra. It also provides equipment for the leprosy hospital outside Katmandu in Nepal. Funds have also been made available for research which has led to a breakthrough in healing neural disorders in leprosy patients. In the distant past, many of those who were afflicted by a wide variety of other skin diseases joined the Order. As a result, in more recent times, the Order has become involved with the treatment of all types of skin diseases, and, to this end, the Grand Priory of England and Wales collaborates with other charities working in this field. Help for the handicapped and the aged has been added to our traditional concerns, and to this has been help for the terminally ill, thus bringing the Grand Priory into the realms of the hospice movement. The Order is active in all aspects of international relief complementing the work of similar bodies such as the British Red Cross and the Order of St John in a collaborative way. In some countries the Order has a Volunteer Emergency Corps which operates ambulance services.

One of the Missions of the New Zealand Order of St. Lazarus is to Disseminate Information About Leprosy in the West Pacific Area, and to aid those who are treating lepers through financial arrangements.

In November 1991, at the request of the Grand Master, the Grand Hospitaller of the Order convened a meeting of European Hospitallers to consider the danger to Christian civilization posed by restlessness and instability in the countries of Eastern Europe, at that time being plagued by famine, disease and economic catastrophe. As a result, the Order has distributed a huge quantity of relief supplies throughout Eastern Europe, including Russia, Poland, the Czech and Slovak Republics, Hungary and Croatia. Particularly prominent in this work has been the Lazarus-Hilfswerk based in Germany, which working under the auspices of the E.E.C., dispatched over 20 million dollars worth of aid in over 300 convoys to the needy of Poland. In 1992 the E.E.C. decided to send 125 million dollars worth of aid to the needy of Russia, and gave the responsibility for its distribution jointly to the Red Cross and the Order of Saint Lazarus. This humanitarian work in Europe was particularly well supported by the Order's Jurisdictions in the USA and Canada.

In Germany there are two fundamentally different organizations within the Order. The first is the Grand Bailiwick, which is the conventional chivalric arm of the Order, which consists of voluntary workers who provide funds and material aid on a very large scale, both locally and internationally. The second is called the Lazarus Hilfswerk, an humanitarian offshoot of the Order, to which the German state provides two thirds funding, the remainder coming from donations and modest charges for services. These humanitarian services are rendered to the community by young men and women who volunteer to serve in the Lazarus Hilfswerk, which is classed as an alternative to military service. They volunteer to serve for a longer period than they would be obliged to do had they chosen to do their conscription time in the Armed Forces. Within the Lazarus Hilfswerk, these young people are under a military style discipline, wear a distinctive uniform and are paid as they would have been if they served in the military. They have at their disposal fleets of vans, ambulances, mobile kitchens, 'buses, lorries and rolling stock. A highly sophisticated control centre, located in Hurth, a suburb of Cologne, organizes their local and international aid missions. In addition to these young people, who are only obliged to work locally, are volunteers who, together with the Red Cross, take large quantities of aid on behalf of the European Community, to Russia, Poland, and other parts of the former USSR, as well as other disaster areas.