The present invention is directed to forms II, III, V, VI, VII, VIII, IX and X of sertraline hydrochloride and novel methods for their preparation. According to the present invention, sertraline hydrochloride polymorph II may be produced by slurrying sertraline hydrochloride polymorph VI in aprotic organic solvent. Sertraline hydrochloride polymorphic form III may be produced by heating sertraline hydrochloride polymorphs V and VI. Sertraline hydrochloride forms V and VI may be produced from either sertraline hydrochloride or sertraline base by crystallization. Sertraline hydrochloride Form VII may be produced by suspending sertraline chloride polymorph V in water, followed by filtration. Sertraline hydrochloride Forms VIII and IX may be produced by suspending sertraline base in water followed by acidification and filtration. Sertraline hydrochloride Form X may be produced by suspending sertraline hydrochloride in benzyl alcohol with heating, followed by filtration.