Abstract. The purpose of this paper is to give an explicit formula of the Lojasiewicz exponent of an isolated weighted homogeneous singularity in terms of its weights.Let f : (C n , 0) → (C, 0) be a holomorphic function with an isolated critical point at 0.It is well known(see [10]) that the Lojasiewicz exponent can be calculated by means of analytic pathswhere ord(φ) := inf i {ord(φ i )} for φ ∈ C{t} n . By definition, we put ord(0) = +∞.Lojasiewicz exponents have important applications in singularity theory, for instance, Teissier [22] showed that C 0 -sufficiency degree of f (i.e., the minimal integer r such that f is topologically equivalent to f + g for all g with ord(g)Despite deep research of experts in singularity theory, it is not proved yet that Lojasiewicz exponent L(f ) is a topological invariant of f (in contrast to the Milnor number). An interesting mathematical problem is to give formulas for L(f ) in terms of another invariants of f or an algorithm to compute it. In the two-dimensional case there are many explicit formulas for L(f ) in various terms (see The aim of this paper is to compute the Lojasiewicz exponent for the classes of weighted homogeneous isolated singularities in terms of the weights. In particular, we generalize a formula for L(f ) of Krasiński, Oleksik and P loski [8] for weighted homogeneous surface singularity. This was already announced by Tan, Yau and Zuo [21], but thier paper seems to have some gaps in the proof of proposition 3.4. We were motived by their papers. However, our considerations are based on other ideas. More precisely, we use the notion of weighted homogenous filtration introduced by Paunescu in [18], the geometric characterization of µ-constancy in [12,22] and the result of Varchenko [23], which described the µ-constant stratum of weighted homogeneous singularities in terms of the mixed Hodge structures.Moreover, we show that the Lojasiewicz exponent is invariant for all µ-constant deformation of weighted homogeneous singularity, which gives an affirmative partial answer to Teissier's conjecture [22].