Few data are available on the quantitative assessment of complexity (C), especially in relation to a patient's exposure to radiation. The relationship between several clinical (CFs), anatomic (AFs), and technical factors (TFs) versus fluoroscopy time (FT) was evaluated in 402 random percutaneous transluminal coronary angioplasty (PTCA) procedures. CFs were age, sex, single or multivessel disease, ejection fraction, and previous coronary artery bypass graft. AFs were assessed based on the American Heart Association / American College of Cardiology classification. TFs were multivessel PTCA, use of the double wire or double balloon technique, stenting, ostial stenting, bifurcation stenting, and intravascular ultrasonography. No CFs significantly influenced FT, whereas all AFs and TFs (except multivessel PTCA) did significantly influence FT. A scoring system was developed, and two complexity indexes (CI) were conceived, based on which the procedures were divided into three groups: simple, medium, and complex. The mean FTs were 471+/-289, 805+/-532, and 1,190+/-641 (P <0.0001), respectively. Total cine frame recordings were 1,119+/-572, 1,265+/-644 (P = 0.0355), and 1,418+/-785 (P<0.0001 vs. simple; P = NS vs. medium). The dose/area product measurement was 65.8+/-41.4, 93 +/-58.5 (P<0.0001), and 116.7+/-72.8 (P<0.0001 vs. simple; P = 0.00159 vs. medium), respectively. In our series, CI was directly related to AF and TF, but not to CF. Comparison of PTCA procedures and definition of appropriate FT should consider CIs.