A stable, easy to operate, flow cytometer was built for routine use by research personnel in a biology laboratory. A 5 watt argon-ion laser excites the fluorescent dyes in cells flowing through a quartz flow chamber. A f/0.95 TV camera lens collects the fluorescent and scattered light and directs it through color separation filters and a beam splitter onto two photomultiplier tubes. Two 3-axis positioners are used to align the focused laser beam and the flow chamber with the light collection optics. All of the components, except the laser, are mounted on a rigid aluminum plate. Standard electronics modules are used. A coefficient of variation of about 1% can be obtained with fluorescent microspheres.