Background: In general, patients with a cancer suspicion visit the hospital multiple times before the diagnosis is completed. Using various “operations management” techniques a limited number of fast track diagnostic services were implemented in the Netherlands Cancer Institute (NKI) in 2006. Fast growing patient numbers and increasing process complexity, led to diminished service levels. To decrease the amount of patient visits and period of uncertainty, fast track diagnostics is implemented for 17 cancer types. The in benchmarks proven high efficiency, hardly any redundancy, and no capacity extension made this a large efficiency challenge. We report on the process of redesign, implementation, and first results. Methods: The throughput time (first visit to diagnosis conversation) was measured before redesigning the diagnosis process, and repeated after implementation of fast track diagnostics. In pre-measurement throughput time was retrospectively measured for 105 patients and 7 cancer types. The diagnosis process for 17 cancer types was redesigned by multidisciplinary teams. Input and process variation, slot use and constraints were analysed for all processes. In an eclectic approach, elements from lean management, theory of constraints, and mathematical analysis were used to organize slots for MRI, CT, PET, and echo with reservations turning into capacity available for short-term planning. Results: In premeasurement diagnosis was completed from 2 workdays onward to 58 (mean throughput time 13.3 workdays). It proved possible to design 15 of 18 tumors as a one-stop shop (Table). Through involvement of clinical and board leadership, massive communication efforts, commitment of physicians to reschedule their weekly activities was rather positive. In the post measurement the mean throughput time was 0.8 days (median 0 days). Conclusions: The involvement of physicians in redesigning and reorganizing their work was important: implementation of fast track diagnosis proved successful for 14 out of 17 cancer types. For 3 tumor types fast track diagnosis implementation is designed but not yet completed. Throughput time was considerably shortened after implementation of fast track diagnostics.