A rapid resolution reversed-phase high performance liquid chromatographic (RR RP-HPLC) method has been developed and validated for simultaneous determination of haloperidol and six related compounds. Investigated matrix was a laboratory mixture of a therapeutic active substance haloperidol and its six related compounds in concentration ratio 300:1. Experimental design was used during method optimization (full factorial 23 design) and robustness testing (Central Composite Circumscribed design). Three factors: organic phase variation during gradient elution, flow rate and gradient rise time were independent variables. To estimate the system response during the optimization procedure and robustness testing, resolution (