  This work provides an elementary introduction to the Higgs sector
renormalisation within the Minimal Suppersymmetric Standard Model (MSSM)
framework. The MSSM tree-level relation $m_h^2+m_H^2=m_A^2+m_Z^2$ is
renormalised using the standard technique of direct computation of the relevant
one-loop Feynman diagrams. The expected cancellation of ultraviolet divergences
is explicitly checked and the well-known leading-log term is recovered.
