Neuropsychological assessments were performed on 70 patients referred after a Catacarb chemical release in a Northern California town. After appropriate exclusions, the 59 patients used in the final analysis were mostly White (66%), with 56% having some college level education. They were administered the: Wechsler Adult Intelligence Scale-Revised (WAIS-R), Memory Assessment Scale (MAS), Trails A and B, Stroop, Controlled Oral Word Association Test (COWAT), Fingertapping Test, Purdue Pegboard, Dynamometer, Rey 15-Item Test, Minnesota Multiphasic Personality Inventory-2 (MMPI-2), Brief Symptom Inventory (BSI), Beck Depression Index (BDI), Profile of Mood States (POMS), and Impact of Events Scale (IES) scales in addition to a health questionnaire and symptom checklist. Results indicate impaired scores on mnestic function and information processing when compared to Heaton's (1992) normative data, and the MAS norms (Williams, 1991). MMPI-2, BSI, BDI, POMS, and IES results indicate significant elevations on scales of depression, anxiety, anger, and posttraumatic stress disorder (PTSD) symptoms. The more brief tests of affect and mood appear sufficiently sensitive in measuring the dysphoric mood in group research studies. Clinical diagnoses using criteria from the Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV; American Psychiatric Association, 1994) criteria indicate a prevalence of 54% PTSD and 64% Amnestic or Cognitive disturbance. New onset of dermatological, respiratory, visual, and gastrointestinal symptoms and illnesses are consistent with the chemical exposure, the PTSD may be in reaction to it, and Amnestic/Cognitive disturbance, from both an organic and functional etiology.