We evaluated three desktop instruments suitable for decentralizing the assays of blood cholesterol and triglycerides to satellite and physician's office testing. The instruments, Ektachem DT 60 (E), Reflotron (R), and Seralyzer (S), were used according to their manufacturers' instructions to assay serum or capillary blood from outpatients at two physicians offices. Accuracy was assessed in the centralized laboratory by using an automated centrifugal analyzer (A). The bias of A was monitored with an international quality-control material. We found all instruments easy to handle. Regression equations for cholesterol determinations were: E = 0.92A + 0.7 (n = 331, r = 0.94), R (capillary blood) = 0.96A + 0.3 (n = 256, r = 0.95), and S = 0.93A + 0.6 (n = 260, r = 0.92). For triglycerides we obtained E = 1.02A (n = 331, r = 0.97), R (cap. blood) = 0.88A (n = 213, r = 0.97), R = 0.94A + 0.1 (n = 90, r = 0.99), and S = 0.96A (n = 266, r = 0.98). Duplicate and within-day precision was less than 8%. Between-day precision (during a month) was less than 10%. We stress the need of both laboratory and field evaluation and emphasize the benefit of quality control.