The intent of this study was to determine if HIV seropositivity alters the maximum temperature (T(max)) and WBC count of febrile intravenous (i.v.) drug users with infective endocarditis (IE). A review of 497 charts of patients with endocarditis provided 228 eligible patient visits (46%), with 158 cases (69.3%) of IE among 126 patients (74 HIV+ and 52 HIV-). Mean T(max) for all patients with IE was 39.1 degrees C (102.4 degrees F). Mean T(max) was similar between the HIV+ (39.1 degrees C, 102.4 degrees F) and HIV- (39.2 degrees C, 102.5 degrees F) groups. There were no differences in mean T(max) among HIV+ patients with CD4 counts > 200 (39.0 degrees C, 102.3 degrees F), those with CD4 < or =200 (39.2 degrees C, 102.5 degrees F), and the HIV- group (39.2 degrees C, 102.5 degrees F). Nearly 8% of i.v. drug users with confirmed IE presented to the ED with a T(max) below 37.8 degrees C (100.0 degrees F). Mean WBC count was significantly lower in HIV+ (11.1 k/mm(3)) than in HIV- patients (15.4 k/mm(3)) and significantly lower in the group with CD4 < or =200 (8.0 k/mm(3)) than in the HIV- group. In conclusion, HIV infection was not associated with lower T(max), but it was associated with decreased WBC count in the general HIV+ group and in the group with CD4 < or =200.