A strictly cyclic operator
algebra 𝒜 on a Hilbert space X is a uniformly closed subalgebra of Z(X) such that
𝒜x0= X for some x0 in X. In this paper it is shown that if 𝒜 is a strictly cyclic
self-adjoint algebra, then (i) there exists a finite orthogonal decomposition of
X,X =∑J=1n⊕ Mj, such that each Mj reduces 𝒜 and the restriction of 𝒜
to Mj is strongly dense in Z(Mj) and (ii) the commutant of 𝒜 is finite
dimensional.