We describe the improved properties of the NMHDECAY program, that is designed to compute Higgs and sparticle masses and Higgs decay widths in the NMSSM. In the version 2.0, Higgs decays into squarks and sleptons are included, accompanied by a calculation of the squark, gluino and slepton spectrum and tests against constraints from LEP and the Tevatron. Further radiative corrections are included in the Higgs mass calculation. A link to MicrOMEGAs allows to compute the dark matter relic density, and a rough (lowest order) calculation of BR ( b → s γ ) is performed. Finally, version 2.1 allows to integrate the RGEs for the soft terms up to the GUT scale. Program summary Title of program:NMHDECAY_SCAN, NMHDECAY_SLHA Catalogue identifier:ADXW_v1_0 Program summary URL: http://cpc.cs.qub.ac.uk/summaries/ADXW_v1_0 Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland Licensing provisions:none Programming language used:Fortran Computer:Mac, PC, Sun, Dec, Alpha Operating system:Mac OSX, Linux, Unix, Windows No. of lines in distributed program, including test data, etc.:20 060 No. of bytes in distributed program, including test data, etc.:133 644 RAM:2M bytes Distribution format:tar.gz Number of processors used:1 Classification:11.6 Journal reference of previous version:JHEP 0502:066, 2005 Does the new version supersede the previous version?:Yes Nature of problem:Computation of the Higgs and sparticle spectrum in the NMSSM and check of theoretical and experimental constraints. Solution method:Mass matrices including up to 2 loop radiative corrections for the Higgs bosons and all sparticles are computed and diagonalized. All Higgs decay widths are computed and branching ratios are compared to experimental bounds. Renormalisation group equations are integrated up to the GUT scale using a modified Runge–Kutta method, in order to check for the absence of a Landau pole. A modified version of MicrOmegas_1.3 can be called in order to compute the relic density of the lightest sparticle. Reasons for the new version:Higgs to sparticle decays added, computation of dark matter relic density added. Summary of revisions:Treatment of RGEs and radiative corrections improved, Higgs to sparticle decays added, new link to MicrOmegas_1.3. Restrictions:none Unusual features:none Running time:<1 s per point in parameter space