OBJECTIVE: This investigation sought to study immediate and delayed verbal and visuospatial recall in Parkinson disease (PD) patients with left hemibody (LHO) and right hemibody (RHO) onset of motor symptoms and to examine the role of mental processing speed in recall of this information. BACKGROUND: Research is mixed regarding material specific memory impairments in LHO and RHO PD. However, earlier research has not used a factorial approach in investigating material specific memory in LHO and RHO PD. We hypothesized that LHO PD patients would exhibit an increase in performance following the delayed verbal free recall trial and either decline or stability in performance on the delayed visuospatial free recall trial. The opposite pattern was hypothesized for RHO PD patients. METHOD: The Hopkins Verbal Learning Test-revised (HVLT-R) and the Brief Visuospatial Memory Test-revised (BVMT-R) were administered to a sample of 28 LHO PD patients and 36 RHO PD patients. The Stroop Color-word Test was administered as a measure of mental processing speed. RESULTS: The results indicated that the RHO group experienced a significant decline in performance on verbal free recall from the immediate to the delayed trials and a significant improvement in performance from the immediate to the delayed visuospatial free recall trials. Additionally, a significant negative correlation was found between mental processing speed and changes in recall from the immediate to the delayed conditions for the RHO group. CONCLUSIONS: These results indicate that the RHO PD group experienced a significant decline in verbal free recall and a significant improvement in visuospatial free recall from the immediate to the delayed trials and that the LHO PD patients experienced no significant changes. Further, mental processing speed appears to influence the recall of information from the immediate to the delayed conditions. Copyright © 2010 by Lippincott Williams & Wilkins.