Key words Differential operators, singular boundary conditions, inverse spectral problems MSC (2000) 34A55, 34B24, 34L40, 47E05Dedicated to the memory of F. V. Atkinson Singular boundary conditions are formulated for Sturm-Liouville operators having singularities and turning points at the end-points of the interval. For boundary-value problems with singular boundary conditions, inverse problems of spectral analysis are studied. We give formulations of the inverse problems both for the case of separated and non-separated singular boundary conditions. For each class of inverse problems we prove a uniqueness theorem and give a procedure for constructing the solution of the inverse problem.