A ring R is uniquely (strongly) clean provided that for any a ∈ R there exists a unique idempotent e ∈ R ( e ∈ comm(a)) such that a − e ∈ U (R) . We prove, in this note, that a ring R is uniquely clean and uniquely bleached if and only if R is abelian, Tn(R) is uniquely strongly clean for all n ≥ 1 , i.e. every n × n triangular matrix over R is uniquely strongly clean, if and only if R is abelian, and Tn(R) is uniquely strongly clean for some n ≥ 1 . In the commutative case, more explicit results are obtained.