The value of conventional gamma globulin in prophylaxis of hepatitis A has not been confirmed in recent years but there is no evidence that ineffectiveness has been encountered as a result of declining immune experience among antibody donors in open populations. Fortunately, specific tests for hepatitis A antibody are becoming available as a means of estimating effectiveness of currently manufactured gamma globulin. Hepatitis B prophylaxis by conventional gamma globulin is much more uncertain but the negative evidence must be considered in light of rising anti-HBstiters of globulin manufactured more recently. The latter have appeared to be effective in pre-exposure prophylaxis when non-parenteral transmission was implicated. Post-exposure prophylaxis against massive inocula of hepatitis B, as in transfusions, would appear to require large amounts of HBsantibody. Protection against hepatitis from small inocula accompanying accidental punctures with contaminated needles is under controlled study to determine whether the anti-HBstiter of special globulin preparations is a predictive index of protection. Results are expected by midyear, 1975.