The LED fluorescence macroscope can detect tumor engraftment of single T-ALL cells and is capable of multispectral, real-time imaging. Animals engrafted with a single dsRED-labeled T-ALL cell can be easily distinguished from nonengrafted animals at 45 days after transplantation (n = 1 of 10 fish, A; n = 2 of 20 fish, B; n = 3 of 29 fish panel C) by LED fluorescence macroscopy. Multispectral imaging with the LED fluorescence macroscope (D-I). Still image capture with dual-spectrum imaging of unanesthetized mylz2-Amcyan and mylz2-mCherry transgenic animals (D, blue and black light with 520/40 filter and 640/35 filter), mylz2-GFP and mylz2-mCherry (E, blue light with 520/40 filter and 640/35 filter), and creatine kinase-zsYellow and mylz2-mCherry (F, blue light with 575/52 filter and 640/35 filter). Animals were imaged from below at 30 frames per second, and a single frame is shown. Multispectral imaging also can be used to visualize fluorescent-labeled T-ALLs engrafted into fluorescent recipient animals. A mylz2-mCherry animal engrafted with an Amcyan-labeled T-ALL at 30 days after transplantation imaged by epi-fluorescence stereomicroscopy (G, 7.0× magnification) or by use of the LED fluorescence macroscope (blue light with 480/30 and 640/35 filters; H-I). Panel H shows a control animal (top) along with a dual transgenic leukemic fish (bottom). Three leukemic fish imaged from below at 30 frames per second and a single frame is shown (I). Scale bars are 1 cm in panels A through F and H through I; 2 mm in panel G.