In parallel to the direct search program, LEP made precision measurements of many observables of the weak interactions. These observables are sensitive to the value of the Higgs mass through contributions of processes containing loops of virtual Higgs bosons. This allowed for the first time a direct estimate of the Higgs mass of about 100 ± 30 GeV/ c. This estimate however is subject to the condition that the Standard Model is all there is, and no physics beyond the Standard Model come into play at these energy levels. New physical effects could potentially alter this estimate substantially.